improving-success-rate-protein-crystallization-random-microseed

Improving the Success Rate of Protein Crystallization by Random Microseed Matrix Screening

Random microseed matrix screening  (rMMS) is a protein crystallization technique in which seed crystals are added  to random screens. By increasing the ...

University of Bristol

Recent major flooding in the UK has raised concern that climate change is causing increases in flood frequency and flood magnitude. This paper considers whether UK flood data provide evidence of increasing trends in fluvial floods. The analysis examines both local and national flood series and investigates the effect of climate variability on trend detection. The results suggest that there have been trends towards more protracted high flows over the last 30-50 years, but that this could be accounted for as part of climatic variation rather than climate change. There is no statistical evidence of a long-term trend in flooding over the last 80-120 years. Thus, although climate change could be influencing floods, direct analysis of flood records does not yet provide proof.

Evidence for trends in UK flooding.

Proteins synthesized in the cytosol either remain there or are localized to a specific membrane and subsequently translocated to another cellular compartment. These extracytosolic proteins have to cross, or be inserted into, a phospholipid bilayer-a process governed by membrane-bound protein transporters designed to recognize and receive appropriate polypeptides and thread them through the membrane. One such translocation complex, SecY/Sec61, is found in every cell, in either the plasma membrane of bacteria and archaea or the endoplasmic reticulum membrane of eukaryotes. Recent structural findings, combined with previous genetic and biochemical studies, have helped to describe how the passage of proteins through the membrane might occur, but several points of uncertainty remain.

The structure of the Sec complex and the problem of protein translocation.

In bacteria, the SecA protein associates with a ubiquitous protein channel SecYEG where it drives the post-translational secretion of pre-proteins across the plasma membrane. The high-resolution structures of both proteins have been determined in their resting states; however, the mechanism that couples ATP hydrolysis to active transport of substrate proteins through the membrane is not well understood. An analysis of the steady-state ATPase activity of the enzyme reveals that there is an allosteric binding site for magnesium distinct from that associated with hydrolysis of ATP. We have demonstrated that this regulation involves a large conformational change to the SecA dimer, which exerts a strong influence on the turnover and affinity for ATP, as well as the affinity for ADP. The strong inhibitory influence of magnesium on the ATPase activity can be countered by cardiolipin and conditions that promote protein translocation.

Allosteric regulation of SecA: magnesium-mediated control of conformation and activity.

In bacteria, the SecYEG protein translocation complex employs the cytosolic ATPase SecA to couple the energy of ATP binding and hydrolysis to the mechanical force required to push polypeptides through the membrane. The molecular basis of this energy transducing reaction is not well understood. A peptide-binding array has been employed to identify sites on SecYEG that interact with SecA. These results along with fluorescence spectroscopy have been exploited to characterise a long-distance conformational change that connects the nucleotide-binding fold of SecA to the transmembrane polypeptide channel in SecY. These movements are driven by binding of non-hydrolysable ATP analogues to a monomer of SecA in association with the SecYEG complex. We also determine that interaction with SecYEG simultaneously decreases the affinity of SecA for ATP and inhibitory magnesium, favouring a previously identified active state of the ATPase. Mutants of SecA capable of binding but not hydrolysing ATP do not elicit this conformationally active state, implicating residues of the Walker B motif in the early chain of events that couple ATP binding to the mobility of the channel.

A large conformational change couples the ATP binding site of SecA to the SecY protein channel.

A short helix in the centre of the SecY subunit serves as a 'plug' blocking the protein channel. This site must be vacated if the channel is to open and accommodate translocating protein. We have synthesised a peptide mimic of this plug, and show that it binds to E. coli SecYEG, identifying a distinct and peripheral binding site. We propose that during active translocation the plug moves to this second discrete site and chart its position. Deletion of the plug in SecY increases the stoichiometry of the peptide-SecYEG interaction by also exposing the location it occupies in the channel. Binding of the plug peptide to the channel is unaffected by SecA.

Synthetic peptides identify a second periplasmic site for the plug of the SecYEG protein translocation complex.

The motor protein SecA drives the transport of polypeptides through the ubiquitous protein channel SecYEG. Changes in protein-nucleotide binding energy during the hydrolytic cycle of SecA must be harnessed to drive large conformational changes resulting in channel opening and vectorial substrate polypeptide transport. Here, we elucidate the ATP hydrolysis cycle of SecA from Escherichia coli by transient and steady-state methods. The basal ATPase activity of SecA is very slow with the release of ADP being some 600-fold slower than hydrolysis. Upon binding to SecYEG the release of ADP is stimulated but remains rate-limiting. ADP release is fastest in the fully coupled system when a substrate protein is being translocated; in this case hydrolysis and ADP release occur at approximately the same rate. The data imply that ADP dissociation from SecA is accompanied by a structural rearrangement that is strongly coupled to the protein interface and protein translocation through SecYEG.

Energy transduction in protein transport and the ATP hydrolytic cycle of SecA.

Cardiolipin &#xBC15;&#xD14C;&#xB9AC;&#xC544;&#xC640; &#xBBF8;&#xD1A0; &#xCF58; &#xB4DC;&#xB9AC; &#xC544;&#xC758; &#xC5D0;&#xB108;&#xC9C0; &#xC808;&#xC57D; &#xB0B4; &#xBA74; &#xB9C9;&#xC758; &#xD56D;&#xC0C1; &#xC788;&#xB294; &#xAD6C;&#xC131; &#xC694;&#xC18C;&#xC785;&#xB2C8;&#xB2E4;. &#xAD6C;&#xC870;&#xB294; &#xBCC0;&#xC870;&#xC640;&#xB294; bilayer&#xC758; &#xC5ED; &#xB3D9;&#xC740; &#xB2E4;&#xC591; &#xD55C; &#xC5F0;&#xAD6C;&#xC640; &#xAC19;&#xC774; &#xADF8;&#xB4E4;&#xC758; &#xAC70;&#xC8FC; &#xB2E8;&#xBC31;&#xC9C8;&#xC758; &#xD65C;&#xB3D9;&#xC5D0; &#xBBF8;&#xCE58;&#xB294; &#xC601;&#xD5A5;. &#xC5EC;&#xAE30;&#xC5D0; &#xC6B0;&#xB9AC;&#xAC00; cardiolipin &#xB098; &#xB780;, &#xD65C;&#xB3D9;, &#xBC0F; &#xB2E8;&#xBC31;&#xC9C8; &#xC804; &#xAE30;&#xACC4;&#xC758; &#xC9C0;&#xC5ED;&#xD654;&#xC5D0; &#xACB0;&#xACFC; &#xBD84;&#xC11D;. Cardiolipin &#xADF8;&#xB7EC;&#xC790; &#xADF8;&#xAC83; &#xC548;&#xC815;&#xD654;&#xB97C; dimer SecA Atpase&#xC5D0; &#xB300; &#xD55C; &#xB192;&#xC740; &#xC120;&#xD638;&#xB3C4; &#xBC14;&#xC778;&#xB529; &#xC11C;&#xD53C;&#xC2A4;&#xB97C; &#xC0DD;&#xC131; &#xD558; &#xACE0; ATP &#xAC00;&#xC218;&#xBD84;&#xD574; &#xC790;&#xADF9; SecYEG &#xB2E8;&#xBC31;&#xC9C8; &#xCC44;&#xB110; &#xBCF5;&#xC7A1; &#xD558; &#xACE0; &#xAE34;&#xBC00; &#xD558; &#xAC8C; &#xC5F0;&#xACB0; &#xD569;&#xB2C8;&#xB2E4;. &#xAD6C;&#xC870;&#xC640; &#xAE30;&#xB2A5;&#xC5D0; &#xBBF8;&#xCE58;&#xB294; &#xC601;&#xD5A5; &#xBFD0;&#xB9CC; &#xC544;&#xB2C8;&#xB77C; &#xB2E8;&#xC9C0;&#xC758; subcellular &#xBC30;&#xD3EC; &#xB9C9; cardiolipin &#xB0B4;&#xC6A9;&#xC5D0; &#xC758;&#xD574; &#xC218;&#xC815; &#xB429;&#xB2C8;&#xB2E4;. &#xD568;&#xAED8;, &#xACB0;&#xACFC; &#xC138;&#xD3EC; &#xB9C9;&#xC5D0;&#xC11C; &#xBC1C;&#xC0DD; &#xD558;&#xB294; &#xC5D0;&#xB108;&#xC9C0; &#xC758;&#xC874; &#xBC18;&#xC751;&#xC758; &#xAD11;&#xBC94;&#xC704; &#xD55C; &#xBC94;&#xC704;&#xC640; &#xAD00;&#xB828;&#xC774; &#xC788;&#xC744; &#xAC83;&#xC73C;&#xB85C; &#xBCF4;&#xC778;&#xB2E4; &#xD544;&#xC218;&#xC801;&#xC778; &#xAD50;&#xD1B5; &#xBCF5;&#xC7A1; &#xD558; &#xACE0;, &#xC778;&#xC9C0;&#xC9C8; &#xD589;&#xB3D9;&#xC73C;&#xB85C; &#xD76C;&#xADC0; &#xD558; &#xACE0; &#xD3EC;&#xAD04;&#xC801;&#xC778; &#xD1B5;&#xCC30;&#xB825;&#xC744; &#xC81C;&#xACF5;.

&#xC138;&#xADE0; translocon&#xC5D0; cardiolipin&#xC758; &#xD589;&#xB3D9;&#xC785;&#xB2C8;&#xB2E4;.

&#x5FC3;&#x78F7;&#x8102;&#x662F;&#x8282;&#x80FD;&#x6280;&#x672F;&#x5185;&#x7684;&#x7EC6;&#x83CC;&#x548C;&#x7EBF;&#x7C92;&#x4F53;&#x819C;&#x7684;&#x864E;&#x89C6;&#x7708;&#x7708;&#x7684;&#x7EC4;&#x6210;&#x90E8;&#x5206;&#x3002;&#x5176;&#x8C03;&#x5236;&#x7684;&#x7ED3;&#x6784;&#x548C;&#x53CC;&#x5C42;&#x7684;&#x6D3B;&#x529B;&#x6240;&#x793A;&#x7684;&#x4E00;&#x4E9B;&#x7814;&#x7A76;&#x5DF2;&#x5F71;&#x54CD;&#x5176;&#x9A7B;&#x5730;&#x7684;&#x86CB;&#x767D;&#x8D28;&#x7684;&#x6D3B;&#x6027;&#x3002;&#x5728;&#x8FD9;&#x91CC;&#x6211;&#x4EEC;&#x5206;&#x6790;&#x5FC3;&#x78F7;&#x8102;&#x5BF9;&#x6784;&#x8C61;&#x3001; &#x6D3B;&#x52A8;&#x548C;&#x672C;&#x5730;&#x5316;&#x7684;&#x86CB;&#x767D;&#x6613;&#x4F4D;&#x673A;&#x68B0;&#x9020;&#x6210;&#x7684;&#x540E;&#x679C;&#x3002;&#x5FC3;&#x78F7;&#x8102;&#x7D27;&#x7D27;&#x8054; SecYEG &#x86CB;&#x767D;&#x901A;&#x9053;&#x590D;&#x6742;&#xFF0C;&#x4E8E;&#x662F;&#x5B83;&#x7A33;&#x5B9A;&#x4E8C;&#x805A;&#x4F53;&#x3001; &#x8D5B;&#x5EB7; ATPase&#xFF0C;&#x4E3A;&#x521B;&#x5EFA;&#x4E00;&#x4E2A;&#x9AD8;&#x7684;&#x4EB2;&#x548C;&#x6027;&#x7ED3;&#x5408;&#x9762;&#x548C;&#x523A;&#x6FC0; ATP &#x6C34;&#x89E3;&#x3002;&#x9664;&#x4E86;&#x5BF9;&#x7ED3;&#x6784;&#x548C;&#x529F;&#x80FD;&#x7684;&#x5F71;&#x54CD;&#xFF0C;&#x590D;&#x6742;&#x7684;&#x4E9A;&#x7EC6;&#x80DE;&#x5206;&#x5E03;&#x88AB;&#x4FEE;&#x6539;&#x5FC3;&#x78F7;&#x8102;&#x542B;&#x91CF;&#x7684;&#x819C;&#x3002;&#x5728;&#x4E00;&#x8D77;&#xFF0C;&#x7ED3;&#x679C;&#x63D0;&#x4F9B;&#x7F55;&#x89C1;&#x548C;&#x5168;&#x9762;&#x7684;&#x89C1;&#x89E3;&#x770B;&#x6765;&#x662F;&#x6709;&#x5173;&#x7684;&#x8303;&#x56F4;&#x5E7F;&#x6CDB;&#x7684;&#x80FD;&#x6E90;&#x4F9D;&#x8D56;&#x578B;&#x53CD;&#x5E94;&#x53D1;&#x751F;&#x5728;&#x819C;&#x7684;&#x78F7;&#x8102;&#x4E0A;&#x590D;&#x6742;&#xFF0C;&#x57FA;&#x672C;&#x8FD0;&#x8F93;&#x884C;&#x52A8;&#x3002;

&#x5FC3;&#x78F7;&#x8102;&#x5BF9;&#x7EC6;&#x83CC;&#x7684; translocon &#x64CD;&#x4F5C;&#x3002;

Cardiolipin is an ever-present component of the energy-conserving inner membranes of bacteria and mitochondria. Its modulation of the structure and dynamism of the bilayer impacts on the activity of their resident proteins, as a number of studies have shown. Here we analyze the consequences cardiolipin has on the conformation, activity, and localization of the protein translocation machinery. Cardiolipin tightly associates with the SecYEG protein channel complex, whereupon it stabilizes the dimer, creates a high-affinity binding surface for the SecA ATPase, and stimulates ATP hydrolysis. In addition to the effects on the structure and function, the subcellular distribution of the complex is modified by the cardiolipin content of the membrane. Together, the results provide rare and comprehensive insights into the action of a phospholipid on an essential transport complex, which appears to be relevant to a broad range of energy-dependent reactions occurring at membranes.

The action of cardiolipin on the bacterial translocon.

Cardiolipine est une composante omnipr&eacute;sente des membranes internes des mitochondries et des bact&eacute;ries, &eacute;conomes en &eacute;nergie. Sa modulation de la structure et le dynamisme de la bicouche impact sur l&#39;activit&eacute; de leurs prot&eacute;ines r&eacute;sidents, comme un certain nombre d&#39;&eacute;tudes ont montr&eacute;. Ici, nous analysons les cons&eacute;quences cardiolipine a sur la conformation, l&#39;activit&eacute; et la localisation de la machinerie de translocation des prot&eacute;ines. Cardiolipine associe &eacute;troitement la cha&icirc;ne de prot&eacute;ine de SecYEG complexe, apr&egrave;s quoi il stabilise le dim&egrave;re, cr&eacute;e une surface de liaison de haute affinit&eacute; pour l&#39;ATPase de SecA et stimule l&#39;hydrolyse de l&#39;ATP. Outre les effets sur la structure et la fonction, la distribution subcellulaire du complexe modifie le contenu de la cardiolipine de la membrane. Ensemble, les r&eacute;sultats donnent un aper&ccedil;u rare et complet dans l&#39;action d&#39;un phospholipide sur une essentielle de transport complexe, qui semble &ecirc;tre pertinent &agrave; une vaste gamme de r&eacute;actions d&eacute;pendant de l&#39;&eacute;nergie qui se produisent &agrave; membranes.

L&#39;action de la cardiolipine sur le translocon bact&eacute;rienne.

Cardiolipin ist eine allgegenw&auml;rtige Komponente der energiesparende inneren Membranen von Bakterien und Mitochondrien. Die Modulation der Struktur und Dynamik der Bilayer hat Auswirkungen auf die Aktivit&auml;t ihrer resident Proteine, wie eine Reihe von Studien gezeigt haben. Hier analysieren wir die Folgen, die Cardiolipin auf die Konformation, Aktivit&auml;t und Lokalisierung der Protein Translokation Maschine hat. Cardiolipin verbindet eng mit dem SecYEG-Protein-Channel, der Komplex, woraufhin es die Dimer stabilisiert, eine Oberfl&auml;che mit hoher Affinit&auml;t binden f&uuml;r die SecA schafft ATPase und stimuliert die ATP-Hydrolyse. Neben den Auswirkungen auf die Struktur und Funktion ist die subzellul&auml;re Verteilung des Komplexes von Cardiolipin Inhalt der Membran ge&auml;ndert. Gemeinsam bieten die Ergebnisse selten und umfassende Einblicke in die Handlung der ein Phospholipid Verkehrsausschusses ein wesentlich komplexer, was f&uuml;r eine breite Palette von Energie-abh&auml;ngige Reaktionen auf Membranen relevant zu sein scheint.

Die Aktion von Cardiolipin auf die bakterielle Translokon.

Cardiolipina &egrave; un componente immancabile delle membrane interne risparmio energetico dei batteri e nei mitocondri. La modulazione della struttura e il dinamismo del doppio strato impatti sull&#39;attivit&agrave; delle loro proteine residenti, come un certo numero di studi hanno dimostrato. Qui analizziamo le conseguenze cardiolipina ha la conformazione, attivit&agrave; e localizzazione dei macchinari di traslocazione di proteine. Cardiolipina associa strettamente con il canale di SecYEG protein complex, dopodich&eacute; stabilizza il dimero, crea una superficie ad alta affinit&agrave; di legame per l&#39;atpasi SecA e stimola l&#39;idrolisi dell&#39;ATP. Oltre agli effetti sulla struttura e funzione, la distribuzione subcellulare del complesso viene modificata dal contenuto cardiolipina della membrana. Insieme, i risultati forniscono approfondimenti rare e complete l&#39;azione di un fosfolipide su un trasporto essenziale complesso, che sembra essere rilevante per una vasta gamma di reazioni di energia-dipendente che si verificano a membrane.

L&#39;azione di cardiolipina sul translocon batterica.

&#x30AB;&#x30EB;&#x30B8;&#x30AA;&#x30EA;&#x30D4;&#x30F3;&#x7D30;&#x83CC;&#x3084;&#x30DF;&#x30C8;&#x30B3;&#x30F3;&#x30C9;&#x30EA;&#x30A2;&#x306E;&#x30A8;&#x30CD;&#x30EB;&#x30AE;&#x30FC;&#x7BC0;&#x7D04;&#x306E;&#x5185;&#x5074;&#x306E;&#x819C;&#x306F;&#x3001;&#x5E38;&#x306B;&#x5B58;&#x5728;&#x3059;&#x308B;&#x30B3;&#x30F3;&#x30DD;&#x30FC;&#x30CD;&#x30F3;&#x30C8;&#x3067;&#x3059;&#x3002;&#x7814;&#x7A76;&#x306E;&#x6570;&#x304C;&#x793A;&#x3055;&#x308C;&#x3066;&#x3044;&#x308B;&#x3088;&#x3046;&#x306B;&#x305D;&#x306E;&#x5909;&#x8ABF;&#x69CB;&#x9020;&#x3068;&#x4E8C;&#x91CD;&#x819C;&#x306E;&#x30C0;&#x30A4;&#x30CA;&#x30DF;&#x30BA;&#x30E0;&#x305D;&#x306E;&#x5C45;&#x4F4F;&#x8005;&#x306E;&#x86CB;&#x767D;&#x8CEA;&#x306E;&#x6D3B;&#x52D5;&#x306B;&#x5F71;&#x97FF;&#x3092;&#x4E0E;&#x3048;&#x307E;&#x3059;&#x3002;&#x3053;&#x3053;&#x30AB;&#x30EB;&#x30B8;&#x30AA;&#x30EA;&#x30D4;&#x30F3; &#x30B3;&#x30F3;&#x30DB;&#x30E1;&#x30FC;&#x30B7;&#x30E7;&#x30F3;&#x3001;&#x30A2;&#x30AF;&#x30C6;&#x30A3;&#x30D3;&#x30C6;&#x30A3;&#x3001;&#x304A;&#x3088;&#x3073;&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;&#x8F38;&#x9001;&#x88C5;&#x7F6E;&#x306E;&#x5C40;&#x5728;&#x306B;&#x4E0E;&#x3048;&#x308B;&#x7D50;&#x679C;&#x3092;&#x5206;&#x6790;&#x3057;&#x307E;&#x3059;&#x3002;&#x305D;&#x308C;&#x306F;&#x30C0;&#x30A4;&#x30DE;&#x30FC;&#x3092;&#x5B89;&#x5B9A;&#x5316;&#x3001;&#x9AD8;&#x89AA;&#x548C;&#x6027;&#x7D50;&#x5408;&#x8868;&#x9762;&#x30BB;&#x30AB; ATPase &#x3092;&#x4F5C;&#x6210;&#x3057;&#x3001;ATP &#x52A0;&#x6C34;&#x5206;&#x89E3;&#x53CD;&#x5FDC;&#x3092;&#x523A;&#x6FC0;&#x3059;&#x308B;&#x3068;&#x3059;&#x3050;&#x30AB;&#x30EB;&#x30B8;&#x30AA;&#x30EA;&#x30D4;&#x30F3;&#x306F;&#x3057;&#x3063;&#x304B;&#x308A;&#x3068;&#x8907;&#x96D1;&#x306A;&#x306E;&#x819C;&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;&#x306E;&#x30C1;&#x30E3;&#x30CD;&#x30EB;&#x3092;&#x95A2;&#x9023;&#x4ED8;&#x3051;&#x307E;&#x3059;&#x3002;&#x69CB;&#x9020;&#x3068;&#x6A5F;&#x80FD;&#x306E;&#x5F71;&#x97FF;&#x306B;&#x52A0;&#x3048;&#x3066;&#x3001;&#x8907;&#x5408;&#x4F53;&#x306E;&#x7D30;&#x80DE;&#x5185;&#x5206;&#x819C;&#x30AB;&#x30EB;&#x30B8;&#x30AA;&#x30EA;&#x30D4;&#x30F3; &#x30B3;&#x30F3;&#x30C6;&#x30F3;&#x30C4;&#x306B;&#x3088;&#x3063;&#x3066;&#x5909;&#x66F4;&#x3055;&#x308C;&#x307E;&#x3059;&#x3002;&#x4E00;&#x7DD2;&#x306B;&#x3001;&#x7D50;&#x679C;&#x819C;&#x3067;&#x8D77;&#x3053;&#x308B;&#x30A8;&#x30CD;&#x30EB;&#x30AE;&#x30FC;&#x4F9D;&#x5B58;&#x578B;&#x53CD;&#x5FDC;&#x306E;&#x5E83;&#x3044;&#x7BC4;&#x56F2;&#x306B;&#x95A2;&#x9023;&#x3059;&#x308B;&#x8868;&#x793A;&#x3055;&#x308C;&#x308B;&#x30A2;&#x30AF;&#x30B7;&#x30E7;&#x30F3;&#x306F;&#x672C;&#x8CEA;&#x7684;&#x306A;&#x8F38;&#x9001;&#x306B;&#x8907;&#x96D1;&#x3067;&#x3001;&#x30EA;&#x30F3;&#x8102;&#x8CEA;&#x306E;&#x307E;&#x308C;&#x306A;&#x3001;&#x5305;&#x62EC;&#x7684;&#x306A;&#x6D1E;&#x5BDF;&#x3092;&#x63D0;&#x4F9B;&#x3057;&#x307E;&#x3059;&#x3002;

&#x7D30;&#x83CC;&#x30C8;&#x30E9;&#x30F3;&#x30B9;&#x30ED;&#x30B3;&#x30F3;&#x4E0A;&#x30AB;&#x30EB;&#x30B8;&#x30AA;&#x30EA;&#x30D4;&#x30F3;&#x306E;&#x30A2;&#x30AF;&#x30B7;&#x30E7;&#x30F3;&#x3002;

Cardiolipina es un componente siempre presente de las membranas internas de conservaci&oacute;n de energ&iacute;a de las bacterias y las mitocondrias. Su modulaci&oacute;n de la estructura y el dinamismo de la bicapa impacta en la actividad de sus prote&iacute;nas residentes, como han demostrado varios estudios. Aqu&iacute; analizamos las consecuencias cardiolipina tiene en la conformaci&oacute;n, actividad y localizaci&oacute;n de la maquinaria de translocaci&oacute;n de la prote&iacute;na. Cardiolipina estrechamente asociados con el canal de la prote&iacute;na de SecYEG complejo, con lo cual estabiliza el d&iacute;mero, crea una superficie de uni&oacute;n de alta afinidad para la ATPasa de SecA y estimula la hidr&oacute;lisis de ATP. Adem&aacute;s de los efectos sobre la estructura y funci&oacute;n, se modifica la distribuci&oacute;n subcelular del complejo por el contenido de cardiolipina de la membrana. En conjunto, los resultados proporcionan ideas raras y completas en la acci&oacute;n de un fosfol&iacute;pido en un complejo de transporte esencial que parece ser relevante para una amplia gama de las reacciones dependientes de energ&iacute;a que ocurre en las membranas.

La acci&oacute;n de cardiolipina en el translocon bacteriana.

Protein secretion in bacteria is driven through the ubiquitous SecYEG complex by the ATPase SecA. The structure of SecYEG alone or as a complex with SecA in detergent reveal a monomeric heterotrimer enclosing a central protein channel, yet in membranes it is dimeric. We have addressed the functional significance of the oligomeric status of SecYEG in protein translocation using single molecule and ensemble methods. The results show that while monomers are sufficient for the SecA- and ATP-dependent association of SecYEG with pre-protein, active transport requires SecYEG dimers arranged in the back-to-back conformation. Molecular modeling of this dimeric structure, in conjunction with the new functional data, provides a rationale for the presence of both active and passive copies of SecYEG in the functional translocon.

The oligomeric state and arrangement of the active bacterial translocon.

The Sec complex forms the core of a conserved machinery coordinating the passage of proteins across or into biological membranes. The bacterial complex SecYEG interacts with the ATPase SecA or translating ribosomes to translocate secretory and membrane proteins accordingly. A truncated preprotein competes with the physiological full-length substrate and primes the protein-channel complex for transport. We have employed electron cryomicroscopy of two-dimensional crystals to determine the structure of the complex unlocked by the preprotein. Its visualization in the native environment of the membrane preserves the active arrangement of SecYEG dimers, in which only one of the two channels is occupied by the polypeptide substrate. The signal sequence could be identified along with the corresponding conformational changes in SecY, including relocation of transmembrane segments 2b and 7 as well as the plug, which presumably then promote channel opening. Therefore, we propose that the structure describes the translocon unlocked by preprotein and poised for protein translocation.

Structure of the SecY complex unlocked by a preprotein mimic.

The motor ATPase SecA drives protein secretion through the bacterial Sec complex. The PPXD (pre-protein cross-linking domain) of the enzyme has been observed in different positions, effectively opening and closing a clamp for the polypeptide substrate. We set out to explore the implicated dynamic role of the PPXD in protein translocation by examining the effects of its immobilization, either in the position occupied in SecA alone with the clamp held open or when in complex with SecYEG with the clamp closed. We show that the conformational change from the former to the latter is necessary for high-affinity association with SecYEG and a corresponding activation of ATPase activity, presumably due to the PPXD contacting the NBDs (nucleotide-binding domains). In either state, the immobilization prevents pre-protein transport. However, when the PPXD was attached to an alternative position in the associated SecYEG complex, with the clamp closed, the transport capability was preserved. Therefore large-scale conformational changes of this domain are required for the initiation process, but not for translocation itself. The results allow us to refine a model for protein translocation, in which the mobility of the PPXD facilitates the transfer of pre-protein from SecA to SecYEG.

The dynamic action of SecA during the initiation of protein translocation.

&#x7EC6;&#x83CC;&#x7684; ATPase &#x8D5B;&#x5EB7;&#x548C;&#x86CB;&#x767D;&#x901A;&#x9053;&#x590D;&#x6742; SecYEG &#x6784;&#x6210;&#x7684;&#x6838;&#x5FC3;&#x91CD;&#x8981;&#x7684;&#x86CB;&#x767D;&#x8D28;&#x7684;&#x6613;&#x4F4D;&#x673A;&#x68B0;&#x3002;&#x6BCF;&#x4E2A;&#x5468;&#x671F;&#x7684;&#x9636;&#x6BB5;&#x6C34;&#x89E3; ATP &#x548C;&#x4ED6;&#x4EEC;&#x5982;&#x4F55;&#x8026;&#x5408;&#x5230;&#x86CB;&#x767D;&#x79FB;&#x4F4D;&#x6240;&#x81F4;&#x7684;&#x6784;&#x8C61;&#x53D8;&#x5316;&#x7684;&#x6027;&#x8D28;&#x4E0D;&#x662F;&#x5341;&#x5206;&#x6E05;&#x695A;&#x7684;&#x3002;&#x8D5B;&#x5EB7; SecYEG &#x590D;&#x6742;&#x7684;&#x7ED3;&#x6784;&#x7684;&#x4E00;&#x4E2A;&#x7406;&#x60F3;&#x7684;&#x5730;&#x4F4D;&#x5728;&#x8D5B;&#x5EB7;&#x8054;&#x7CFB;&#x57FA;&#x8D28;&#x86CB;&#x767D;&#x5E76;&#x5C06;&#x5176;&#x63A8;&#x901A;&#x8FC7;&#x819C;&#x900F;&#x9732; 2-&#x87BA;&#x65CB;-&#x624B;&#x6307; (2HF)&#x3002;&#x5947;&#x602A;&#x7684;&#x662F;&#xFF0C;&#x8FD9;&#x4E2A;&#x624B;&#x6307;&#x7684;&#x86CB;&#x767D;&#x901A;&#x9053;&#x8FB9;&#x7F18;&#x7684;&#x56FA;&#x5B9A;&#x5316;&#x4E86;&#x6613;&#x4F4D;&#xFF0C;&#x4E0D;&#x4F1A;&#x5F71;&#x54CD;&#x800C;&#x5176;&#x5B9E;&#x884C;&#x5185;&#x90E8;&#x901A;&#x9053;&#x963B;&#x585E;&#x4EA4;&#x901A;&#x3002;&#x8FD9;&#x79CD;&#x5206;&#x6790;&#x89E3;&#x6790;&#x6D3B;&#x52A8;&#x590D;&#x6742;&#xFF0C;&#x8868;&#x660E;&#x540E;&#x542F;&#x52A8;&#x8FDB;&#x7A0B;&#x6613;&#x4F4D;&#x8981;&#x6C42;&#x53EA;&#x6709;&#x4E00;&#x4E2A;&#x526F;&#x672C;&#x8D5B;&#x5EB7;&#x548C; SecYEG &#x7684;&#x5316;&#x5B66;&#x8BA1;&#x91CF;&#x6BD4;&#x3002;&#x7ED3;&#x679C;&#x4E5F;&#x80FD;&#x91CF;&#x8F6C;&#x5BFC;&#x548C;&#x4F5C;&#x529F;&#x51B2;&#x7A0B;&#x9A7E;&#x9A76;&#x8FD0;&#x8F93;&#x673A;&#x5236;&#x4EA7;&#x751F;&#x91CD;&#x8981;&#x5F71;&#x54CD;&#x3002;&#x7531;&#x6B64;&#x53EF;&#x89C1;&#xFF0C;2HF &#x4E0D;&#x662F;&#x591A;&#x80BD;&#x6613;&#x4F4D;&#x9AD8;&#x5EA6;&#x79FB;&#x52A8;&#x4F20;&#x611F;&#x5143;&#x7D20;&#x3002;

&#x8D5B;&#x5EB7; 2 &#x87BA;&#x65CB;&#x624B;&#x6307;&#x7684;&#x6D41;&#x52A8;&#x6027;&#x4E0D;&#x662F;&#x901A;&#x8FC7;&#x590D;&#x6742;&#x7684; SecYEG &#x7684;&#x591A;&#x80BD;&#x6613;&#x4F4D;&#x7684;&#x5FC5;&#x8981;&#x6761;&#x4EF6;&#x3002;

The bacterial ATPase SecA and protein channel complex SecYEG form the core of an essential protein translocation machinery. The nature of the conformational changes induced by each stage of the hydrolytic cycle of ATP and how they are coupled to protein translocation are not well understood. The structure of the SecA-SecYEG complex revealed a 2-helix-finger (2HF) of SecA in an ideal position to contact the substrate protein and push it through the membrane. Surprisingly, immobilization of this finger at the edge of the protein channel had no effect on translocation, whereas its imposition inside the channel blocked transport. This analysis resolves the stoichiometry of the active complex, demonstrating that after the initiation process translocation requires only one copy each of SecA and SecYEG. The results also have important implications on the mechanism of energy transduction and the power stroke driving transport. Evidently, the 2HF is not a highly mobile transducing element of polypeptide translocation.

Mobility of the SecA 2-helix-finger is not essential for polypeptide translocation via the SecYEG complex.

L&#39;ATPase SecA bact&eacute;riennes et la prot&eacute;ine canal complexe SecYEG forme le noyau d&#39;une machinerie de translocation des prot&eacute;ines essentielles. La nature des changements conformationnels induits par chaque &eacute;tape du cycle de l&#39;ATP et comment ils sont coupl&eacute;s &agrave; la translocation des prot&eacute;ines hydrolytique ne sont pas bien comprises. La structure du complexe SecA-SecYEG a r&eacute;v&eacute;l&eacute; un doigt 2-h&eacute;lice (2HF) de SecA dans une position id&eacute;ale pour communiquer avec la prot&eacute;ine substrat et le pousser &agrave; travers la membrane. &Eacute;tonnamment, immobilisation de ce doigt au bord du canal prot&eacute;ique n&#39;a eu aucun effet sur la translocation, consid&eacute;rant que son imposition &agrave; l&#39;int&eacute;rieur du canal bloqu&eacute; le transport. Cette analyse r&eacute;sout la stoechiom&eacute;trie du complexe actif, d&eacute;montrant qu&#39;apr&egrave;s que la translocation de processus d&#39;initiation ne n&eacute;cessite qu&#39;une seule copie de chaque de SecA et SecYEG. Les r&eacute;sultats ont &eacute;galement des implications importantes sur le m&eacute;canisme de transduction de l&#39;&eacute;nergie et la course de puissance conduite de transport. &Eacute;videmment, le 2HF n&#39;est pas un &eacute;l&eacute;ment transducteur tr&egrave;s mobile de la translocation de polypeptide.

Mobilit&eacute; du SecA 2-helix-doigt n&#39;est pas essentielle pour la translocation de polypeptide par l&#39;interm&eacute;diaire de la SecYEG complexe.

Die bakterielle ATPase SecA und Protein Kanal komplexe SecYEG Form der Kern eine wesentliche Protein Translokation Maschinen. Die Natur der Konformationsver&auml;nderungen induziert durch jedes Stadium des hydrolytische ATP und wie sie zu Protein Translokation gekoppelt sind, sind nicht gut verstanden. Die Struktur des Komplexes SecA-SecYEG ergab einen 2-Helix-Finger (2HF) von SecA in einer idealen Position, wenden Sie sich an das Substrat-Protein und schieben Sie es durch die Membran. Immobilisierung von dieser Finger am Rand des Kanals Protein hatte keine Auswirkung auf die Translokation, w&auml;hrend ihrer Einf&uuml;hrung in den Kanal Verkehr blockiert. Diese Analyse l&ouml;st die St&ouml;chiometrie der aktive Komplex, nachdem die Einleitung Prozess Translokation nur eine Kopie von SecA und SecYEG erfordert vor Augen. Die Ergebnisse haben auch erhebliche Auswirkungen auf den Mechanismus der Energie Transduktion und der Arbeitshub Verkehr fahren. Offenbar ist die 2HF keine hochmobile Lentivirale Element Polypeptid Translokation.

Mobilit&auml;t von der SecA 2 Helix-Finger unbedingt nicht Polypeptid Translokation &uuml;ber die komplexe SecYEG.

La SecA ATPasi batterica e la proteina canale complesso SecYEG forma il nucleo di un macchinario traslocazione di proteine essenziali. La natura dei cambiamenti conformazionali indotte da ogni fase del ciclo idrolitico di ATP e come essi sono accoppiati alla traslocazione di proteine non sono ben compresi. La struttura del complesso SecA-SecYEG ha rivelato un dito 2-helix (2HF) di SecA in una posizione ideale a contatto con la proteina substrato e spingerlo attraverso la membrana. Sorprendentemente, immobilizzazione di questo dito al bordo del canale della proteina ha avuto alcun effetto sulla traslocazione, considerando che la sua imposizione all&#39;interno del canale bloccato trasporto. Questa analisi si risolve la stechiometria del complesso attivo, dimostrando che dopo la traslocazione del processo di iniziazione richiede solo una copia di SecA e SecYEG. I risultati hanno anche importanti implicazioni sul meccanismo di trasduzione di energia e la corsa di potenza guida trasporto. Evidentemente, il 2HF non &egrave; un elemento altamente mobile trasduzione della traslocazione del polipeptide.

Mobilit&agrave; del SecA 2-elica-dito non &egrave; essenziale per traslocazione polipeptide tramite il SecYEG complesso.

&#x7D30;&#x83CC;&#x306E; atp &#x30A2;&#x30FC;&#x30BC; SecA &#x3068;&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;&#x8907;&#x5408;&#x819C;&#x306E;&#x4E2D;&#x6838;&#x3092;&#x6210;&#x3059;&#x3001;&#x4E0D;&#x53EF;&#x6B20;&#x306E;&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;&#x8F38;&#x9001;&#x88C5;&#x7F6E;&#x30C1;&#x30E3;&#x30CD;&#x30EB;&#x3057;&#x307E;&#x3059;&#x3002;ATP &#x3068;&#x86CB;&#x767D;&#x8CEA;&#x3078;&#x306E;&#x8EE2;&#x6D41;&#x306E;&#x7D50;&#x5408;&#x306E;&#x52A0;&#x6C34;&#x5206;&#x89E3;&#x30B5;&#x30A4;&#x30AF;&#x30EB;&#x306E;&#x5404;&#x30B9;&#x30C6;&#x30FC;&#x30B8;&#x306B;&#x3088;&#x3063;&#x3066;&#x8A98;&#x8D77;&#x30B3;&#x30F3;&#x30DB;&#x30E1;&#x30FC;&#x30B7;&#x30E7;&#x30F3;&#x5909;&#x5316;&#x306E;&#x6027;&#x8CEA;&#x306F;&#x3088;&#x304F;&#x7406;&#x89E3;&#x3055;&#x308C;&#x3066;&#x3044;&#x307E;&#x305B;&#x3093;&#x3002;&#x819C;&#x8907;&#x5408;&#x4F53;&#x306E;&#x69CB;&#x9020; 2 &#x30D8;&#x30EA;&#x30C3;&#x30AF;&#x30B9;&#x6307; (2HF) &#x306E;&#x57FA;&#x8CEA;&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;&#x306B;&#x9023;&#x7D61;&#x3057;&#x3001;&#x819C;&#x3092;&#x901A;&#x3057;&#x3066;&#x30D7;&#x30C3;&#x30B7;&#x30E5;&#x3059;&#x308B;&#x30BB;&#x30AB;&#x7406;&#x60F3;&#x7684;&#x306A;&#x4F4D;&#x7F6E;&#x3067;&#x660E;&#x3089;&#x304B;&#x306B;&#x3057;&#x307E;&#x3057;&#x305F;&#x3002;&#x30C8;&#x30E9;&#x30F3;&#x30B9;&#x30DD;&#x30FC;&#x30C8;&#x306E;&#x8CE6;&#x8AB2;&#x30C1;&#x30E3;&#x30F3;&#x30CD;&#x30EB;&#x306E;&#x5185;&#x5074;&#x306E;&#x30D6;&#x30ED;&#x30C3;&#x30AF;&#x306B;&#x5BFE;&#x3057;&#x9A5A;&#x3044;&#x305F;&#x3053;&#x3068;&#x306B;&#x3001;&#x3053;&#x306E;&#x6307;&#x86CB;&#x767D;&#x8CEA;&#x30C1;&#x30E3;&#x30CD;&#x30EB;&#x306E;&#x7AEF;&#x306E;&#x56FA;&#x5B9A;&#x5316;&#x306B;&#x306F;&#x8EE2;&#x6D41;&#x3001;&#x52B9;&#x679C;&#x304C;&#x306A;&#x304B;&#x3063;&#x305F;&#x3002;&#x3053;&#x306E;&#x5206;&#x6790;&#x306F;&#x3001;&#x958B;&#x59CB;&#x30D7;&#x30ED;&#x30BB;&#x30B9;&#x8EE2;&#x5EA7;&#x30BB;&#x30AB;&#x3068;&#x819C;&#x306E; 1 &#x3064;&#x3060;&#x3051;&#x30B3;&#x30D4;&#x30FC;&#x3092;&#x5FC5;&#x8981;&#x3068;&#x3057;&#x305F;&#x3089;&#x3001;&#x305D;&#x308C;&#x3092;&#x793A;&#x3059;&#x30A2;&#x30AF;&#x30C6;&#x30A3;&#x30D6;&#x8907;&#x5408;&#x4F53;&#x306E;&#x5316;&#x5B66;&#x91CF;&#x8AD6;&#x3092;&#x89E3;&#x6C7A;&#x3057;&#x307E;&#x3059;&#x3002;&#x7D50;&#x679C;&#x306F;&#x307E;&#x305F;&#x30A8;&#x30CD;&#x30EB;&#x30AE;&#x30FC;&#x4F1D;&#x9054;&#x3068;&#x8F38;&#x9001;&#x306E;&#x904B;&#x8EE2;&#x30D1;&#x30EF;&#x30FC; &#x30B9;&#x30C8;&#x30ED;&#x30FC;&#x30AF;&#x306E;&#x30E1;&#x30AB;&#x30CB;&#x30BA;&#x30E0;&#x306E;&#x91CD;&#x8981;&#x306A;&#x542B;&#x610F;&#x304C;&#x3042;&#x308A;&#x307E;&#x3059;&#x3002;&#x660E;&#x3089;&#x304B;&#x306B;&#x3001;2HF &#x30DD;&#x30EA;&#x30DA;&#x30D7;&#x30C1;&#x30C9;&#x8EE2;&#x6D41;&#x306E;&#x9AD8;&#x5EA6;&#x306A;&#x30E2;&#x30D0;&#x30A4;&#x30EB;&#x5909;&#x63DB;&#x8981;&#x7D20;&#x3067;&#x306F;&#x3042;&#x308A;&#x307E;&#x305B;&#x3093;&#x3002;

&#x30BB;&#x30AB; 2-&#x30D8;&#x30EA;&#x30C3;&#x30AF;&#x30B9;-&#x6307;&#x306E;&#x30E2;&#x30D3;&#x30EA;&#x30C6;&#x30A3;&#x306F;&#x30DD;&#x30EA;&#x30DA;&#x30D7;&#x30C1;&#x30C9;&#x8EE2;&#x5EA7;&#x8907;&#x96D1;&#x306A;&#x819C;&#x3092;&#x4ECB;&#x3057;&#x3066;&#x306E;&#x305F;&#x3081;&#x5FC5;&#x9808;&#x3067;&#x306F;&#x3042;&#x308A;&#x307E;&#x305B;&#x3093;&#x3002;

&#xC138;&#xADE0;&#xC131; ATPase Seca&#xC640; &#xB2E8;&#xBC31;&#xC9C8; &#xD544;&#xC218; &#xB2E8;&#xBC31;&#xC9C8; &#xC804; &#xAE30;&#xACC4;&#xC758; &#xBCF5;&#xC7A1; &#xD55C; SecYEG &#xC591;&#xC2DD; &#xD575;&#xC2EC; &#xCC44;&#xB110;. &#xC5B4;&#xB5BB;&#xAC8C; &#xADF8;&#xB4E4;&#xC774; &#xB2E8;&#xBC31;&#xC9C8; &#xC804; &#xD558; &#xACB0;&#xD569; &#xD558;&#xB294; ATP&#xC758; &#xAC00;&#xC218;&#xBD84;&#xD574; &#xC8FC;&#xAE30;&#xC758; &#xAC01; &#xB2E8;&#xACC4;&#xC5D0; &#xC758;&#xD574; &#xC720;&#xB3C4; &#xB41C; &#xAD6C;&#xC870;&#xC801; &#xBCC0;&#xD654;&#xC758; &#xD2B9;&#xC131;&#xC744; &#xC798; &#xC774;&#xD574; &#xD558;&#xC9C0;. SecA SecYEG &#xBCF5;&#xC7A1; &#xD55C; &#xAD6C;&#xC870;&#xC758; &#xAE30;&#xD310; &#xB2E8;&#xBC31;&#xC9C8;&#xC5D0; &#xC5F0;&#xB77D; &#xD558;&#xB294; &#xBA64;&#xBE0C;&#xB808;&#xC778;&#xC744; &#xD1B5;&#xD574; &#xBC00;&#xC5B4; SecA &#xC774;&#xC0C1;&#xC801;&#xC778; &#xC704;&#xCE58;&#xC5D0;&#xC11C;&#xC758; 2-&#xD5EC;&#xB9AD;&#xC2A4;-&#xD551;&#xAC70; (2HF)&#xB97C; &#xACF5;&#xAC1C; &#xD588;&#xB2E4;. &#xB180;&#xB78D;&#xAC8C;&#xB3C4;, immobilization &#xB2E8;&#xBC31;&#xC9C8; &#xCC44;&#xB110;&#xC758; &#xAC00;&#xC7A5;&#xC790;&#xB9AC;&#xC5D0;&#xC774; &#xC190;&#xAC00;&#xB77D;&#xC758; &#xCC44;&#xB110; &#xC548;&#xC5D0; &#xADF8;&#xAC83;&#xC758; &#xBD80;&#xACFC; &#xCC28;&#xB2E8; &#xC804;&#xC1A1; &#xD558;&#xB294; &#xBC18;&#xBA74; &#xC804;&#xC5D0; &#xC544;&#xBB34;&#xB7F0; &#xC601;&#xD5A5;&#xC744; &#xBBF8;&#xCE58;&#xC9C0;&#xB97C; &#xD588;&#xB2E4;. &#xC774; &#xBD84;&#xC11D; &#xD6C4; &#xAC1C;&#xC2DC; &#xACFC;&#xC815; &#xC804; SecA Secyeg&#xC758; &#xAC01; &#xD558;&#xB098;&#xC758; &#xBCF5;&#xC0AC;&#xBCF8;&#xB9CC; &#xD544;&#xC694; &#xD558; &#xC2DC;&#xC5F0; &#xD65C;&#xC131;&#xD654; &#xB2E8;&#xC9C0;&#xC758; stoichiometry&#xB97C; &#xD574;&#xACB0; &#xD569;&#xB2C8;&#xB2E4;. &#xACB0;&#xACFC; &#xB610;&#xD55C; &#xC5D0;&#xB108;&#xC9C0; &#xBCC0;&#xD658; &#xBC0F; &#xC804;&#xC1A1; &#xC6B4;&#xC804; &#xC804;&#xC6D0; &#xC120; &#xBA54;&#xCEE4;&#xB2C8;&#xC998;&#xC5D0; &#xC911;&#xC694; &#xD55C; &#xC601;&#xD5A5;&#xC744; &#xBBF8;&#xCE60;. &#xACB0;&#xAD6D;,&#xB294; 2HF polypeptide &#xC804; &#xC88C;&#xC758; &#xB192;&#xC740; &#xBAA8;&#xBC14;&#xC77C; transducing &#xC694;&#xC18C;&#xB294; &#xC544;&#xB2C8;&#xB2E4;.

SecA 2 &#xB098;&#xC120;-&#xC190;&#xAC00;&#xB77D;&#xC758; &#xC774;&#xB3D9;&#xC131;&#xC740; &#xBCF5;&#xC7A1; &#xD55C; SecYEG &#xD1B5;&#xD574; polypeptide &#xC804; &#xD544;&#xC218;&#xC801;&#xC785;&#xB2C8;&#xB2E4;.

La ATPasa SecA y prote&iacute;na bacteriana canal complejo SecYEG forma la base de un mecanismo de desplazamiento de prote&iacute;na esencial. La naturaleza de los cambios conformacionales inducidos por cada etapa del ciclo hidrol&iacute;tico de ATP y c&oacute;mo se juntan a la translocaci&oacute;n de prote&iacute;nas no son bien entendidos. La estructura del complejo SecA-SecYEG revel&oacute; un dedo 2-h&eacute;lice (2HF) de SecA en una posici&oacute;n ideal en contacto con la prote&iacute;na sustrato y p&aacute;selo a trav&eacute;s de la membrana. Sorprendentemente, inmovilizaci&oacute;n de este dedo en el borde del canal prote&iacute;na no tuvo efecto sobre desplazamiento, mientras que su imposici&oacute;n dentro del canal hab&iacute;a bloqueado el transporte. Este an&aacute;lisis resuelve la estequiometr&iacute;a del complejo activo, demostrando despu&eacute;s de la translocaci&oacute;n del proceso de iniciaci&oacute;n requiere solamente una copia de la SecA y SecYEG. Los resultados tambi&eacute;n tienen importantes implicaciones sobre el mecanismo de transducci&oacute;n de la energ&iacute;a y el transporte de conducci&oacute;n del movimiento de la energ&iacute;a. Evidentemente, el 2HF no es un elemento altamente m&oacute;vil Transductoras de desplazamiento del polip&eacute;ptido.

Article	Year
Evidence for trends in UK flooding. Philosophical transactions. Series A, Mathematical, physical, and engineering sciences\| PubMed ID: 12804252	2002
The structure of the Sec complex and the problem of protein translocation. EMBO reports\| PubMed ID: 17077865	2006
Allosteric regulation of SecA: magnesium-mediated control of conformation and activity. The Journal of biological chemistry\| PubMed ID: 17416585	2007
A large conformational change couples the ATP binding site of SecA to the SecY protein channel. Journal of molecular biology\| PubMed ID: 17964601	2007
Synthetic peptides identify a second periplasmic site for the plug of the SecYEG protein translocation complex. FEBS letters\| PubMed ID: 19084013	2009
Energy transduction in protein transport and the ATP hydrolytic cycle of SecA. Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 19273842	2009
The action of cardiolipin on the bacterial translocon. Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 20479269	2010
The oligomeric state and arrangement of the active bacterial translocon. The Journal of biological chemistry\| PubMed ID: 21056980	2011
Structure of the SecY complex unlocked by a preprotein mimic. Cell reports\| PubMed ID: 22576621	2012
The dynamic action of SecA during the initiation of protein translocation. The Biochemical journal\| PubMed ID: 23126322	2013
Mobility of the SecA 2-helix-finger is not essential for polypeptide translocation via the SecYEG complex. The Journal of cell biology\| PubMed ID: 23209305	2012

Alice Robson

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