Name: defining substrate specificities for lipase and phospholipase candidates
Uploaded: 2016-11-23T12:30:00
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Este trabalho foi financiado por doações do Consejo Nacional de Ciencias y Tecnología-México (CONACyT-México) (82614, 153998, 253549 e 178359 em Investigación Científica Básica, bem como 118 em Investigación en Fronteras de la Ciencia) e da Dirección General de Asuntos de pessoal Académico-Universidad Nacional Autónoma de México (UNAM DGAPA-; PAPIIT IN202616, IN203612).

1. O clone e gene estrutural para sobre-expressar a lipase Previsto <ol><li> Usando reacção em cadeia da polimerase (PCR) 14 e oligonucleótidos específicos (Tabela 1) 15, amplificar o gene de interesse (smc01003, smc00930, ou smc00171), previsto para codificar para uma lipase ou fosfolipase, a partir do ADN genómico do organismo hospedeiro (ou seja , S. meliloti). <ol><li> Introduzir locais específicos de restrição (com a sequ?...

<ol>
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Biotechnol. 13 (4), 390-397 (2002).</li><li>Dowhan, W., Bogdanov, M., Mileykovskaya, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+roles+of+lipids+in+membranes.">Functional roles of lipids in membranes.</a> Biochemistry of Lipids, Lipoproteins and Membranes. , 1-37 (2008).</li><li>Dowhan, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+basis+for+membrane+phospholipid+diversity:+why+are+there+so+many+lipids?.">Molecular basis for membrane phospholipid diversity: why are there so many lipids?.</a> Annu. Rev. Biochem. 66, 199-232 (1997).</li><li>De Rudder, K. E. E., Thomas-Oates, J. E., Geiger, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rhizobium+meliloti+mutants+deficient+in+phospholipid+N-methyltransferase+still+contain+phosphatidylcholine.">Rhizobium meliloti mutants deficient in phospholipid N-methyltransferase still contain phosphatidylcholine.</a> J. Bacteriol. 179, 6921-6928 (1997).</li><li>Geiger, O., R&#246;hrs, V., Weissenmayer, B., Finan, T. M., Thomas-Oates, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+regulator+gene+phoB+mediates+phosphate+stress-controlled+synthesis+of+the+membrane+lipid+diacylglyceryl-N,N,N-trimethylhomoserine+in+Rhizobium+(Sinorhizobium)+meliloti.">The regulator gene phoB mediates phosphate stress-controlled synthesis of the membrane lipid diacylglyceryl-N,N,N-trimethylhomoserine in Rhizobium (Sinorhizobium) meliloti.</a> Mol. Microbiol. 32 (1), 63-73 (1999).</li><li>Klug, R. M., Benning, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+enzymes+of+diacylglyceryl-O-4'-(N,N,N,-trimethyl)homoserine+biosynthesis+are+encoded+by+btaA+and+btaB+in+the+purple+bacterium+Rhodobacter+sphaeroides.">Two enzymes of diacylglyceryl-O-4'-(N,N,N,-trimethyl)homoserine biosynthesis are encoded by btaA and btaB in the purple bacterium Rhodobacter sphaeroides.</a> Proc. Natl. Acad. Sci. USA. 98 (10), 5910-5915 (2001).</li><li>Zavaleta-Pastor, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sinorhizobium+meliloti+phospholipase+C+required+for+lipid+remodeling+duringphosphorus+limitation.">Sinorhizobium meliloti phospholipase C required for lipid remodeling duringphosphorus limitation.</a> Proc. Natl. Acad. Sci. USA. 107 (1), 302-307 (2010).</li><li>Pech-Canul, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FadD+is+required+for+utilization+of+endogenous+fatty+acids+released+from+membrane+lipids.">FadD is required for utilization of endogenous fatty acids released from membrane lipids.</a> J. Bacteriol. 193 (22), 6295-6304 (2011).</li><li>Banerji, S., Flieger, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patatin-like+proteins:+a+new+family+of+lipolytic+enzymes+present+in+bacteria?.">Patatin-like proteins: a new family of lipolytic enzymes present in bacteria?.</a> Microbiology. 150 (Pt 3), 522-525 (2004).</li><li>Sahonero-Canavesi, D. X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fatty+acid-releasing+activities+in+Sinorhizobium+meliloti+include+unusual+diacylglycerol+lipase.">Fatty acid-releasing activities in Sinorhizobium meliloti include unusual diacylglycerol lipase.</a> Environ. Microbiol. 17 (9), 3391-3406 (2015).</li><li>Fischer, M., Pleiss, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Lipase+Engineering+Database:+a+navigation+and+analysis+tool+for+protein+families.">The Lipase Engineering Database: a navigation and analysis tool for protein families.</a> Nucl. Acid. Res. 31 (1), 319-321 (2003).</li><li>Sigrist, C. J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+and+continuing+developments+at+PROSITE.">New and continuing developments at PROSITE.</a> Nucleic Acids Res. 41 (Database issue), D344-D347 (2013).</li><li>Lorenz, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymerase+Chain+Reaction:+Basic+Protocol+Plus+Troubleshooting+and+Optimization+Strategies.">Polymerase Chain Reaction: Basic Protocol Plus Troubleshooting and Optimization Strategies.</a> J. Vis. Exp. (63), e3998 (2012).</li><li>Untergasser, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primer3+-+new+capabilities+and+interfaces.">Primer3 - new capabilities and interfaces.</a> Nucl. 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B., Allen, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microvolume+Protein+Concentration+Determination+using+the+NanoDrop+2000c+Spectrophotometer.">Microvolume Protein Concentration Determination using the NanoDrop 2000c Spectrophotometer.</a> J. Vis. Exp. (33), e1610 (2009).</li><li>Bligh, E. G., Dyer, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+method+for+total+lipid+extraction+and+purification.">A rapid method for total lipid extraction and purification.</a> Can. J. Biochem. Physiol. 37 (8), 911-917 (1959).</li><li>Molecular Dynamics. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Phosphorimager SI User&#180;s Guide. , (1994).</li><li>Dixon, M., Webb, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Enzymes: Third Edition. , (1979).</li><li>Rudolph, A. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression,+characterization,+and+mutagenesis+of+the+Yersinia+pestis+murine+toxin,+a+phospholipase+D+superfamily+member.">Expression, characterization, and mutagenesis of the Yersinia pestis murine toxin, a phospholipase D superfamily member.</a> J. Biol. Chem. 274 (17), 11824-11831 (1999).</li><li>Kato, S., Yoshimura, T., Hemmi, H., Moriyama, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biochemical+analysis+of+a+novel+lipolytic+enzyme+YvdO+from+Bacillus+subtilis.">Biochemical analysis of a novel lipolytic enzyme YvdO from Bacillus subtilis.</a> Biosci. Biotechnol. Biochem. 74 (4), 701-706 (2010).</li><li>Peppelenbosch, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinome+profiling.">Kinome profiling.</a> Scientifica (Cairo). , (2012).</li><li>Manafi, M., Kneifel, W., Bascomb, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorogenic+and+chromogenic+substrates+used+in+bacterial+diagnostics.">Fluorogenic and chromogenic substrates used in bacterial diagnostics.</a> Microbiol. Rev. 55 (3), 335-348 (1991).</li><li>Kuznetsova, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enzyme+genomics:+Application+of+general+enzymatic+screens+to+discover+new+enzymes.">Enzyme genomics: Application of general enzymatic screens to discover new enzymes.</a> FEMS Microbiol. Rev. 29 (2), 263-279 (2005).</li><li>Scopes, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Protein Purification, Principles and Practice. , (2010).</li><li>Geiger, O., Lopez-Lara, I. M., Sohlenkamp, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phosphatidylcholine+biosynthesis+and+function+in+bacteria.">Phosphatidylcholine biosynthesis and function in bacteria.</a> Biochim. Biophys. Acta. 1831 (3), 503-513 (2013).</li></ol>

Nos últimos 20 anos, os genomas de muitos organismos já foram seqüenciados e, apesar de uma riqueza de dados seqüência do genoma foi gerado, interpretação funcional está ficando para trás e, portanto, dificulta a nossa compreensão da função do genoma. funções dos genes em genomas são frequentemente atribuídos com base na similaridade com genes de função ou a ocorrência de motivos conservados conhecido. No entanto, a função exacta de um determinado gene, muitas vezes não é conhecido. Especialmente,...

Lípidos à base de glicerol como triglicerídeos e fosfolipídios (glicero) constituem importante e, provavelmente, as classes de lípidos mais conhecidos 1. Triacilgliceróis (tags) são as gorduras e óleos, que normalmente funcionam como lipídios de armazenamento e, portanto, como potenciais fontes de energia e de carbono. As tags podem ser degradados por lipases, que são frequentemente segregadas pelo organismo produtor de digerir TAGs externas e torná-los disponíveis como fontes de carbono. Além disso, lipases têm sido amplamente estudados ao longo dos anos devido às suas importantes aplicações biotecnológicas 2. Devido à sua natureza anfifílica e sua forma quase cilíndrica, propriedades de formação de membrana (glicero) fosfolipídios de exposição e normalmente constituem os principais componentes lipídicos de uma membrana de bicamada 3. Em microorganismos simples, tais como a bactéria Escherichia coli, apenas três variantes principais grupo de cabeça, fosfatidilglicerol (PG), a cardiolipina (CL), e phosphatidylethanolamine (PE) são encontrados, embora se deva ter presente que cada um deles pode ser substituído com um número considerável de diferentes cadeias de acilo gordo na posição sn-1 ou sn posição -2 dando origem a um grande número de diferentes espécies moleculares 4 . Outras bactérias pode ter outros fosfolipídios em adição ou em vez disso. Por exemplo, Sinorhizobium meliloti, uma bactéria do solo, que é capaz de formar uma simbiose nódulo da raiz de fixação de azoto, com a alfafa de leguminosas (Medicago sativa), contém, além de um segundo fosfolípido PE zwitteriónico, fosfatidilcolina (PC) 5. Além disso, os lipídios não contendo fósforo ou glicerol pode ser anfifílico e fazem parte da membrana celular. Por exemplo, em condições de crescimento limitativos de fósforo, em S. meliloti, (glicero) fosfolípidos são em grande parte substituído por lípidos da membrana que não contêm fósforo, ou seja, os sulfolípidos, lípidos ornitina, e diacylglyceryl trimethylhomoserine (DGTS) 6. Em bactérias, DGTS é formado a partir de diacilglicerol (DAG) em uma via de duas etapas 7, mas a fonte para geração de DAG não foi claro. Experimentos pulse-chase sugeriu que o PC pode ser um precursor para DGTS 8 e utilizando a metodologia descrita neste manuscrito foi possível identificar uma fosfolipase C (PLCP, SMc00171) que é formado sob condições limitantes de fósforo e que pode converter PC em DAG e fosfocolina 8. Em um estudo separado, descobrimos que uma sintetase de acil-CoA (FADD) -deficient mutante de S. meliloti ou de Escherichia coli acumulada ácidos graxos livres ao entrar em fase estacionária de crescimento de 9. Embora estes ácidos gordos pareceu ser derivados de lípidos da membrana, a origem exacta para os ácidos gordos livres ou a enzima (s) libertando-os não eram conhecidos. Mais uma vez, empregando a estratégia delineada neste manuscrito, dois 10 (fosfo) lipases patatina-like (SMc00930 e SMc01003) que contribuiu para a formação de ácidos gordos livres em S. meliloti 11 foram previstos. Surpreendentemente, SMc01003 DAG utilizado como substrato para convertê-lo e, finalmente, monoacilglicerol glicerol e ácidos gordos livres 11. Por conseguinte, é uma lipase SMc01003 DAG (DGLA). Embora um número de algoritmos de previsão do potencial existe (fosfo) lipases 12,13, a sua função precisa e papel fisiológico normalmente não é conhecido. Aqui destacamos um protocolo, clonar e sobre-expressar lipases (fosfo) previstos ou potenciais. Este manuscrito explica como ensaios de enzimas pode ser desenvolvido e optimizado para o (fosfo) lipase sobre-expresso utilizando substratos cromogénicos artificiais. Nós fornecemos exemplos como com um ensaio enzimático otimizado do real (fosfo) lipase substrato podem ser encontradas e como estas descobertas podem enriquecer a nossa compreensão da fisiologia microbiana.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Chloroform</td>
			<td>JT Baker</td>
			<td>9180-03</td>
			<td>TLC analysis &#38; Lipid extraction</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>JT Baker</td>
			<td>9070-03</td>
			<td>TLC analysis &#38; Lipid extraction</td>
		</tr>
		<tr>
			<td>Acetic Acid</td>
			<td>JT Baker</td>
			<td>9507-05</td>
			<td>TLC analysis &#38; Lipid extraction</td>
		</tr>
		<tr>
			<td>Hexanes</td>
			<td>JT Baker</td>
			<td>9309-02</td>
			<td>TLC analysis &#38; Lipid extraction</td>
		</tr>
		<tr>
			<td>Diethylether</td>
			<td>Sigma</td>
			<td>32203</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>bidistilled water</td>
			<td>&#160;ANY</td>
			<td>&#160;NA</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Sigma</td>
			<td>T-1503</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>HCl</td>
			<td>Baker</td>
			<td>9535-02</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Baker</td>
			<td>3624-01</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma</td>
			<td>X-100</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>LB broth</td>
			<td>ANY</td>
			<td>NA</td>
			<td>Bacterial growth, 10g tryptone + 5g yeast extract + 10g NaCl per liter of bidistilled water</td>
		</tr>
		<tr>
			<td>tryptone</td>
			<td>Becton Dickinson and Company</td>
			<td>211705</td>
			<td>Bacterial growth</td>
		</tr>
		<tr>
			<td>yeast extract</td>
			<td>Becton Dickinson and Company</td>
			<td>212750</td>
			<td>Bacterial growth</td>
		</tr>
		<tr>
			<td>TY broth</td>
			<td>ANY</td>
			<td>NA</td>
			<td>Bacterial growth, 8g tryptone + 3g yeast extract + 66mg CaCl2 2 H20 per liter of bidistilled water</td>
		</tr>
		<tr>
			<td>CaCl2 2 H2O</td>
			<td>Baker</td>
			<td>1332-01</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>isopropyl-&#946;-D-thiogalactoside (IPTG)</td>
			<td>Invitrogen</td>
			<td>15529-019</td>
			<td>Bacterial growth</td>
		</tr>
		<tr>
			<td>Diethanolamine</td>
			<td>Sigma</td>
			<td>D-8885</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>MnCl2</td>
			<td>Sigma</td>
			<td>221279</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>Phospholipase A2 snake venom</td>
			<td>Sigma</td>
			<td>P0790</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>Phospholipase C Clostridium perfingrens</td>
			<td>Sigma</td>
			<td>P7633</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>Bis-p-nitrophenyl phosphate</td>
			<td>Sigma</td>
			<td>07422AH</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>p-nitrophenyl stearate</td>
			<td>Sigma</td>
			<td>N3627</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>p-nitrophenyl dodecanoate</td>
			<td>Sigma</td>
			<td>61716</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>p-nitrophenyl decanoate</td>
			<td>Sigma</td>
			<td>N0252</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>p-nitrophenyl palmitate</td>
			<td>Sigma</td>
			<td>N2752</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>p-nitrophenyl butyrate</td>
			<td>Sigma</td>
			<td>N9876</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>p-nitrophenyl octanoate</td>
			<td>Sigma</td>
			<td>21742</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>Acetic Acid, sodium salt [1-14C]</td>
			<td>Perkin Elmer</td>
			<td>NEC084</td>
			<td>Bacterial growth</td>
		</tr>
		<tr>
			<td>dimethylsulfoxide (DMSO)</td>
			<td>JT Baker</td>
			<td>9224-01</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>Aluminium HPTLC silica gel 60 plates. Silica gel HPTLC plates size 20 x 20 cm, 25 sheets.</td>
			<td>Merck</td>
			<td>105547</td>
			<td>TLC analysis &#38; Lipid extraction</td>
		</tr>
		<tr>
			<td>Spectrometer UV/VIS Lambda 35</td>
			<td>Perkin Elmer</td>
			<td>NA</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>Storm 820 Phosphorimager</td>
			<td>Molecular Dynamics</td>
			<td>NA</td>
			<td>Photostimulable Luminescence scanner&#160;</td>
		</tr>
		<tr>
			<td>Multipurpose Scintillation Counter</td>
			<td>Beckman Coulter</td>
			<td>NA</td>
			<td>Radioactivity Quantification</td>
		</tr>
		<tr>
			<td>French Pressure Cell</td>
			<td>ThermoSpectronic</td>
			<td>NA&#160;</td>
			<td>Breakage of cells</td>
		</tr>
		<tr>
			<td>chromatography paper 3MM Chr</td>
			<td>Whatman</td>
			<td>3030917</td>
			<td>TLC analysis</td>
		</tr>
		<tr>
			<td>Sinorhizobium meliloti 1021our</td>
			<td>reference 34</td>
			<td></td>
			<td>studied strain</td>
		</tr>
		<tr>
			<td>Escherichia coli BL21 (DE3) pLysS Competent cells</td>
			<td>Novagen</td>
			<td>69451</td>
			<td>protein expression strain</td>
		</tr>
		<tr>
			<td>pET9a vector</td>
			<td>Novagen</td>
			<td>69431</td>
			<td>protein expression vector</td>
		</tr>
		<tr>
			<td>pET17b vector</td>
			<td>Novagen</td>
			<td>69663</td>
			<td>protein expression vector</td>
		</tr>
		<tr>
			<td>sterile polystyrene round-bottom tube (14 ml) Falcon</td>
			<td>Becton Dickinson</td>
			<td>352057</td>
			<td>radiolabeling of bacterial cultures</td>
		</tr>
		<tr>
			<td>polypropylene microcentrifuge tubes (1.5 ml)</td>
			<td>Eppendorf</td>
			<td>30125.15</td>
			<td>Enzymatic assays</td>
		</tr>
		<tr>
			<td>1,2-dipalmitoyl-sn-glycerol</td>
			<td>Sigma</td>
			<td>D9135</td>
			<td>lipid standard</td>
		</tr>
		<tr>
			<td>L-&#945;-phosphatidylcholine, dipalmitoyl</td>
			<td>Sigma</td>
			<td>P6267</td>
			<td>lipid standard</td>
		</tr>
		<tr>
			<td>DL-&#945;-monopalmitin</td>
			<td>Sigma</td>
			<td>M1640</td>
			<td>lipid standard</td>
		</tr>
		<tr>
			<td>palmitic acid</td>
			<td>Sigma</td>
			<td>P0500</td>
			<td>lipid standard</td>
		</tr>
	</tbody>
</table>

defining substrate specificities for lipase and phospholipase candidates

Microorganismos produzem um largo espectro de lipases (fosfo) que são secretadas, a fim de fazer substratos externos disponível para o organismo. Alternativamente, outros (fosfo) lipase pode ser fisicamente associado com o organismo produtor causando uma rotação de lípidos intrínsecas e frequentemente dando origem a uma remodelação das membranas celulares. Embora potenciais (fosfo) lipase pode ser previsto com um certo número de algoritmos quando a sequência do gene / proteína está disponível, não tem frequentemente sido obtida prova experimental das actividades enzimáticas, especificidades de substrato, e funções fisiológicas potenciais. Este manuscrito descreve a optimização das condições de ensaio para a (fosfo) lipase prospectivos com especificidades de substrato desconhecidos e como empregar estas condições optimizadas na pesquisa para o substrato natural de um respectivo (fosfo) lipase. Usando substratos cromogénicos artificiais, tais como derivados de p-nitrofenilo, pode ajudar a detectar uma menoractividade enzimática para um (fosfo) lipase previsto, sob condições padrão. Tendo encontrado uma actividade enzimática, tais menor, os parâmetros distintos de um ensaio de enzima podem ser variados de modo a obter uma hidrólise mais eficiente do substrato artificial. Depois de ter determinado as condições sob as quais uma enzima funciona bem, uma variedade de substratos naturais potenciais devem ser ensaiadas quanto à sua degradação, um processo que pode ser seguido utilizando métodos cromatográficos diferentes. A definição das especificidades de substrato para enzimas novas, frequentemente fornece hipóteses para um potencial papel fisiológico destas enzimas, que podem então ser testados experimentalmente. Seguindo essas orientações, fomos capazes de identificar uma fosfolipase C (SMc00171) que degrada fosfatidilcolina para fosfocolina e diacilglicerol, em um passo crucial para a remodelação das membranas na bactéria Sinorhizobium meliloti das condições de limitação de fósforo de crescimento. Para duas previu patatin-como fosfolipases (SMc00930 e SMc01003) do mesmo organismo, que poderia redefinir suas especificidades de substrato e esclarecer que SMc01003 é uma lipase diacilglicerol.

Actividade de Fosfolipase específico para PC C SMc00171 com bis-p-nitrofenil fosfato Extractos isentos de células obtidos a partir de E. coli BL21 (DE3) pLysS x, que tinha smc00171 expressa, foram estudados quanto à sua capacidade para hidrolisar ésteres de fosfato de bis-p-nitrofenilo, utilizando um ensaio espectrofotom...

Watch this Scientific Journal Video about Defining Substrate Specificities for Lipase and Phospholipase Candidates at JoVE.com

Defining Substrate Specificities for Lipase and Phospholipase Candidates

Many predicted (phospho)lipases are poorly characterized with regard to their substrate specificities and physiological functions. Here we provide a protocol to optimize enzyme activities, search for natural substrates, and propose physiological functions for these enzymes.

Definindo substrato Especificidades para a lipase e fosfolipase candidatos

Microorganisms produce a wide spectrum of (phospho)lipases that are secreted in order to make external substrates available for the organism. ...

The overall goal of this procedure is to accelerate the detection of physiological substrates for potential lipases and phosopholipases. This method can help answer key questions in the Entomology field, such as how phospholipases contribute to lipid remodeling in biological membranes. The main advantage of this technique is that the optimization of enzymatic activity and the search for the natural substrate for the enzyme can be performed independently.Though this method can provide insight into substrate specificity of bacterial lipases and phospholipases, it can also be modified to study hydrolases of any other model organisms. We first had the idea for this method when we searched for an enzyme activity that could degrade the intrinsic membrane lipid phosphatidylcholine inorhizobium meliloti. To prepare cell-free protein extracts, defrost bacterial cell suspensions and store them on ice.Then, pass the cell suspensions three times through a cold pressure cell at 20, 000 pounds per square inch. Remove the in-tact cells and cell debris by centrifugation at 5, 000 times g for 30 minutes, at four degrees Celsius. After centrifugation, prepare aliquots of 100 and 500 microliters from the supernatant for subsequent analysis.Set up the previously-optimized enzyme assay using the pipetting schemes tabulated in the text protocol. For an initial coverage of distinct enzyme activities, use artificial substrates that yield a colored product upon hydrolysis, such as para-nitrophenol or PNP derivatives. Follow the time course for an increase of absorbance at 405 nanometers, due to the formation of PNP in a spectrophotometer at 30 degrees Celsius over a five-minute period.Finally, perform calculations as described in the text protocol. For radio labeling of lipids, prepare an overnight pre-culture of an organism of interest in five milliliters of the desired culture medium and grow at 30 degrees Celsius. From the pre-culture, inoculate into 20 millimeters of fresh medium in a 100-millimeter culture flask, to obtain an initial optical density at 620 nanometers of 0.3 for the culture.Next, transfer a one-milliliter aliquot of the culture to a 14-milliliter sterile polystyrene round bottom tube under sterile conditions. Add one microcurie of 114 c acetate to the one-milliliter culture. Then, incubate the liquid culture under agitation at 30 degrees Celsius for a period of 24 hours.At the end of the incubation period, transfer the culture to a 1.5 milliliter microcentrifuge tube and centrifuge at 12, 000 times g at room temperature for five minutes. Resuspend the pellet in 100 microliters of water. At this point, store the cell suspension at minus 20 degrees Celsius or immediately continue with the extraction of polar lipids.To perform the extraction of polar lipids, add 375 microliters of a two to one methanol to chloroform solution to the 100 microliters of aqueous cell suspension. Vortex the sample for 30 seconds before incubating for five minutes at room temperature. Following incubation, centrifuge for five minutes at 12, 000 times g at room temperature.Then, transfer the supernatant to a new 1.5 milliliter microcentrifuge tube. Next, add 125 microliters of chloroform and 125 microliters of water to the supernatant. After vortexing for 30 seconds, centrifuge the sample for one minute at 12, 000 times g at room temperature.Transfer the lower chloroform phase to a fresh tube. Then, dry the solution with a stream of nitrogen gas. Dissolve the dried lipids in 100 microliters of chloroform to methanol solution.For separation of neutral polar lipids by thin layer chromatography, apply three microliter aliquots of the lipid samples, on a high performance thin-layer chromatography silica gel aluminum sheet, starting two centimeters from the edges of the plate. If multiple samples are analyzed in one-dimensional chromatography, keep a distance of at least 1.5 centimeters between the different sample application spots. Transfer the mobile phase to a TLC developing chamber, internally coated with chromatography paper.Cover with a glass plate to let the chamber saturate for 30 minutes. Transfer the HPTLC Silica Gel aluminum sheet with the dried lipid samples to the chamber. Allow the plate to develop for 30 minutes in a closed chamber before removing the plate.Then, let the solvents dry off in a flow hood for two hours. Once the developed TLC sheet is dry, incubate it with a photostimulable luminescence screen in a closed cassette for three days. Then, expose the incubated screen to a PSL scanner and acquire a virtual image of the separated radio-labeled lipids.To determine diacylglycerol, or DAG, lipase activity, first add 5, 000 CPM of 14 C-labeled DAG to a 1.5 milliliter microcentrifuge tube. Also, add a solution of Triton X-100 to the tube and mix by vortex. Dry the solution under a stream of nitrogen.For a final 100 microliter assay, add Tris-HCl buffer, a sodium chloride solution, and bi-distilled water. Vortex for five seconds. Initiate the reaction by adding five microliters of enzyme to the solution.Incubate the solution at 30 degrees Celsius for four hours. Stop the reaction by the addition of 250 microliters of methanol and 125 microliters of chloroform, before extracting lipids as described earlier in this video. Proceed to analyze neutral polar lipids by 1DTLC and subsequent PSL imaging as before.Although the predicted phosopholipase SMc01003 shows activity with artificial para-nitrophenol acyl esters, the activity is only double or triple of the background activity present in cell-free extracts of Escherichia coli, in which no foreign gene had been expressed. This indicates that para-nitrophenyl acyl esters don't seem to be good substrates for SMc01003. Whereas cell-free extracts of E.Coli cannot degrade diacylglycerol, extracts of strains in which the predicted phospholipase, SMc01003, had been expressed, caused a degradation of diacylglycerol.Though SMc01003 was predicted to be a phospholipase, it is actually a diacylglycerol lipase that degrades diacylglycerol to monoacylglycerol and one fatty acid. It then degrades monoacylglycerol further to glycerol and another fatty acid. Once mastered, this technique can be done in a few weeks if it's performed properly.After watching this video, you should have a good understanding of how to optimize enzyme activities of lipases and phospholipases, and how to continue with the search for their physiological substrates. A crucial advantage of this procedure is that the optimization of the enzyme activity can be separated from the search for the natural enzyme substrate. Don't forget that working with organic solvents or radioactive substances can be extremely hazardous and the required precautions should always be taken while performing this procedure.

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