SMP, SR and AKS acknowledge the fellowships received from the National Institute of Science Education and Research, Department of Atomic Energy. RS acknowledges intramural funding support from the Department of Atomic Energy, and this work is supported through a research grant to RS (BT/PR42977/MED/29/1603/2022) from the Department of Biotechnology (DBT). The authors also acknowledge V Badireenath Konkimalla for his comments, suggestions, and discussions throughout the development of the protocol.

1. Expression of GFP-tagged bacterial cytoskeleton proteins in S. pombe
NOTE: Please see Table 1 for information on all plasmids and strains used here. Please see Table 2 for all media compositions.
<ol>
	<li>Perform cloning of E. coli MreB with an N-terminal GFP fusion (GFP-MreB) and S. aureus FtsZ carrying a C-terminal GFP (SaFtsZ-GFP) into the S. pombe expression vector, pREP42 with a medium-strength t...

Identifying Drugs that Affect Polymerization of Bacterial Cytoskeletal Proteins

<ol>
	<li>Antimicrobial Resistance Collaborators. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+burden+of+bacterial+antimicrobial+resistance+in+2019:+a+systematic+analysis.">Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis.</a> Lancet. 399 (10325), 629-655 (2022).</li><li>Haselbeck, R., 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=Comprehensive+essential+gene+identification+as+a+platform+for+novel+anti-infective+drug+discovery.">Comprehensive essential gene identification as a platform for novel anti-infective drug discovery.</a> Curr Pharma Des. 8 (13), 1155-1172 (2002).</li><li>Wang, J., 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=Discovery+of+a+small+molecule+that+inhibits+cell+division+by+blocking+FtsZ,+a+novel+therapeutic+target+of+antibiotics.">Discovery of a small molecule that inhibits cell division by blocking FtsZ, a novel therapeutic target of antibiotics.</a> J Biol Chem. 278 (45), 44424-44428 (2003).</li><li>Sanchez, S., Demain, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Antibiotics: current innovations and future trends. , (2015).</li><li>Vollmer, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+prokaryotic+cytoskeleton:+a+putative+target+for+inhibitors+and+antibiotics.">The prokaryotic cytoskeleton: a putative target for inhibitors and antibiotics.</a> Appl Microbiol Biotechnol. 73 (1), 37-47 (2006).</li><li>Vollmer, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+the+bacterial+Z-ring.">Targeting the bacterial Z-ring.</a> Chem Biol. 15 (2), 93-94 (2008).</li><li>Kusuma, K. D., Payne, M., Ung, A. T., Bottomley, A. L., Harry, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FtsZ+as+an+antibacterial+target:+status+and+guidelines+for+progressing+this+avenue.">FtsZ as an antibacterial target: status and guidelines for progressing this avenue.</a> ACS Infect Dis. 5 (8), 1279-1294 (2019).</li><li>Kaul, M., Zhang, Y., Parhi, A. K., Lavoie, E. J., Pilch, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+RND-type+efflux+pumps+confers+the+FtsZ-directed+prodrug+TXY436+with+activity+against+Gram-negative+bacteria.">Inhibition of RND-type efflux pumps confers the FtsZ-directed prodrug TXY436 with activity against Gram-negative bacteria.</a> Biochem Pharmacol. 89 (3), 321-328 (2014).</li><li>Casiraghi, A., Suigo, L., Valoti, E., Straniero, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+bacterial+cell+division:+A+binding+site-centered+approach+to+the+most+promising+inhibitors+of+the+essential+protein+FtsZ.">Targeting bacterial cell division: A binding site-centered approach to the most promising inhibitors of the essential protein FtsZ.</a> Antibiotics. 9 (2), 69 (2020).</li><li>Piddock, L. J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multidrug-resistance+efflux+pumps+-+not+just+for+resistance.">Multidrug-resistance efflux pumps - not just for resistance.</a> Nat Rev. Microbiol. 4 (8), 629-636 (2006).</li><li>K&#228;ufer, N. F., Simanis, V., Nurse, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fission+yeast+Schizosaccharomyces+pombe+correctly+excises+a+mammalian+RNA+transcript+intervening+sequence.">Fission yeast Schizosaccharomyces pombe correctly excises a mammalian RNA transcript intervening sequence.</a> Nature. 318 (6041), 78-80 (1985).</li><li>Vyas, A., Freitas, A. V., Ralston, Z. A., Tang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fission+yeast+Schizosaccharomyces+pombe:+A+unicellular+micromammal+model+organism.">Fission yeast Schizosaccharomyces pombe: A unicellular micromammal model organism.</a> Curr Prot. 1 (6), e151 (2021).</li><li>Edwards, D. H., Thomaides, H. B., Errington, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Promiscuous+targeting+of+Bacillus+subtilis+cell+division+protein+DivIVA+to+division+sites+in+Escherichia+coli+and+fission+yeast.">Promiscuous targeting of Bacillus subtilis cell division protein DivIVA to division sites in Escherichia coli and fission yeast.</a> EMBO J. 19 (11), 2719-2727 (2000).</li><li>Srinivasan, R., Mishra, M., Murata-Hori, M., Balasubramanian, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Filament+formation+of+the+Escherichia+coli+actin-related+protein,+MreB,+in+fission+yeast.">Filament formation of the Escherichia coli actin-related protein, MreB, in fission yeast.</a> Curr Biol. 17 (3), 266-272 (2007).</li><li>Srinivasan, R., Mishra, M., Wu, L., Yin, Z., Balasubramanian, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+bacterial+cell+division+protein+FtsZ+assembles+into+cytoplasmic+rings+in+fission+yeast.">The bacterial cell division protein FtsZ assembles into cytoplasmic rings in fission yeast.</a> Gene Dev. 22 (13), 1741-1746 (2008).</li><li>TerBush, A. D., Osteryoung, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+functions+of+chloroplast+FtsZ1+and+FtsZ2+in+Z-ring+structure+and+remodeling.">Distinct functions of chloroplast FtsZ1 and FtsZ2 in Z-ring structure and remodeling.</a> J Cell Biol. 199 (4), 623-637 (2012).</li><li>Sharma, A. K., 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=A+mechanism+of+salt+bridge-mediated+resistance+to+FtsZ+inhibitor+PC190723+revealed+by+a+cell-based+screen.">A mechanism of salt bridge-mediated resistance to FtsZ inhibitor PC190723 revealed by a cell-based screen.</a> Mol Biol Cell. 34 (3), ar16 (2023).</li><li>Basi, G., Schmid, E., Maundrell, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TATA+box+mutations+in+the+Schizosaccharomyces+pombe+nmt1+promoter+affect+transcription+efficiency+but+not+the+transcription+start+point+or+thiamine+repressibility.">TATA box mutations in the Schizosaccharomyces pombe nmt1 promoter affect transcription efficiency but not the transcription start point or thiamine repressibility.</a> Gene. 123 (1), 131-136 (1993).</li><li>Moreno, M. B., Dur&#225;n, A., Carlos Ribas, 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+family+of+multifunctional+thiamine-repressible+expression+vectors+for+fission+yeast.">A family of multifunctional thiamine-repressible expression vectors for fission yeast.</a> Yeast. 16 (9), 861-872 (2000).</li><li>Green, M. R., Sambrook, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Caring+for+Escherichia+coli.">Caring for Escherichia coli.</a> Cold Spring Harb Protoc. , (2018).</li><li>Green, M. R., Sambrook, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+quantification+of+DNA.">Isolation and quantification of DNA.</a> Cold Spring Harb Protoc. , (2018).</li><li>B&#228;hler, J., 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=Heterologous+modules+for+efficient+and+versatile+PCR-based+gene+targeting+in+Schizosaccharomyces+pombe.">Heterologous modules for efficient and versatile PCR-based gene targeting in Schizosaccharomyces pombe.</a> Yeast. 14 (10), 943-951 (1998).</li><li>Pande, V., Mitra, N., Bagde, S. R., Srinivasan, R., Gayathri, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Filament+organization+of+the+bacterial+actin+MreB+is+dependent+on+the+nucleotide+state.">Filament organization of the bacterial actin MreB is dependent on the nucleotide state.</a> J Cell Biol. 221 (5), e202106092 (2022).</li><li>Schindelin, J., 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=Fiji:+an+open-source+platform+for+biological-image+analysis.">Fiji: an open-source platform for biological-image analysis.</a> Nat Meth. 9 (7), 676-682 (2012).</li><li>Zhang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Machine+learning+for+enumeration+of+cell+colony+forming+units.">Machine learning for enumeration of cell colony forming units.</a> Vis Comput Ind Biomed Art. 5 (1), 26 (2022).</li><li>Moen, 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=Deep+learning+for+cellular+image+analysis.">Deep learning for cellular image analysis.</a> Nat Meth. 16 (12), 1233-1246 (2019).</li><li>Higaki, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+evaluation+of+cytoskeletal+organizations+by+microscopic+image+analysis.">Quantitative evaluation of cytoskeletal organizations by microscopic image analysis.</a> Plant Morphol. 29 (1), 15-21 (2017).</li><li>Henty-Ridilla, J. L., Li, J., Day, B., Staiger, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ACTIN+DEPOLYMERIZING+FACTOR4+regulates+actin+dynamics+during+innate+immune+signaling+in+Arabidopsis.">ACTIN DEPOLYMERIZING FACTOR4 regulates actin dynamics during innate immune signaling in Arabidopsis.</a> Plant Cell. 26 (1), 340-352 (2014).</li><li>Boudaoud, 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=an+ImageJ+plug-in+to+quantify+fibrillar+structures+in+raw+microscopy+images.">an ImageJ plug-in to quantify fibrillar structures in raw microscopy images.</a> Nat Protoc. 9 (2), 457-463 (2014).</li><li>Butler, M. S., Paterson, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibiotics+in+the+clinical+pipeline+in+October+2019.">Antibiotics in the clinical pipeline in October 2019.</a> J Antibio. 73 (6), 329-364 (2019).</li><li>Andreu, J. M., Huecas, S., Ara&#250;jo-Baz&#225;n, L., V&#225;zquez-Villa, H., Mart&#237;n-Fontecha, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+search+for+antibacterial+inhibitors+targeting+cell+division+protein+ftsz+at+its+nucleotide+and+allosteric+binding+sites.">The search for antibacterial inhibitors targeting cell division protein ftsz at its nucleotide and allosteric binding sites.</a> Biomedicines. 10 (8), 1825 (2022).</li><li>Vje&#353;tica, 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=A+toolbox+of+stable+integration+vectors+in+the+fission+yeast+Schizosaccharomyces+pombe.">A toolbox of stable integration vectors in the fission yeast Schizosaccharomyces pombe.</a> J Cell Sci. 133 (1), jcs240754 (2020).</li><li>Berg, S., 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=ilastik:+interactive+machine+learning+for+(bio)image+analysis.">ilastik: interactive machine learning for (bio)image analysis.</a> Nat Meth. 16 (12), 1226-1232 (2019).</li><li>Shaevitz, J. W., Gitai, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+structure+and+function+of+bacterial+actin+homologs.">The structure and function of bacterial actin homologs.</a> Cold Spring Harb Pers Biol. 2 (9), a000364 (2010).</li><li>Hoffman, C. S., Wood, V., Fantes, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+ancient+yeast+for+young+geneticists:+A+primer+on+the+Schizosaccharomyces+pombe+model+system.">An ancient yeast for young geneticists: A primer on the Schizosaccharomyces pombe model system.</a> Genetics. 201 (2), 403-423 (2015).</li><li>Aoi, Y., 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=Dissecting+the+first+and+the+second+meiotic+divisions+using+a+marker-less+drug-hypersensitive+fission+yeast.">Dissecting the first and the second meiotic divisions using a marker-less drug-hypersensitive fission yeast.</a> Cell Cycle. 13 (8), 1327-1334 (2014).</li><li>Zhang, J., 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=Improving+drug+sensitivity+of+HIV-1+protease+inhibitors+by+restriction+of+cellular+efflux+system+in+a+fission+yeast+model.">Improving drug sensitivity of HIV-1 protease inhibitors by restriction of cellular efflux system in a fission yeast model.</a> Pathogens. 11 (7), 804 (2022).</li></ol>

All the authors declare no conflicts of interest.

Antimicrobial resistance (AMR) is a serious global health threat, and there is an urgent need for new antibiotics with novel targets. The bacterial cytoskeleton has emerged as an attractive target for developing new antibiotics, with small molecule inhibitors of the cell division protein FtsZ, such as TXA709, already in Phase-I clinical trials30. Several methods have been developed to identify inhibitors of FtsZ polymerization7,31. We have...

The widespread resistance to nearly all antibiotics presently employed to combat bacterial infections has created an immediate necessity for novel categories of antibiotics. A 2019 report indicated that antibiotic-resistant infections resulted in the loss of 1.27 million lives, contributing to an overall tally of 4.95 million deaths when considering complications from resistant bacterial infections1. While still effective in clinical practice, the current arsenal of antibiotics predominantly targets a narrow spectrum of cellular processes, primarily focusing on cell wall, DNA, and protein synthesis. Over the past half-century, fewer than 30 proteins have been commercially exploited as targets for the development of new anti-bacterials2,3. This limited range of viable targets significantly creates constraints to discovering new antibiotics or their derivatives for combating antibiotic-resistant bacteria. Thus, to overcome the emerging antibiotic resistance problem, there is a need for the development of new antibiotics with novel targets and mechanisms of action.
An antibacterial target should ideally be an essential component of bacterial cell growth, be conserved throughout the phylogenetically diverse species, show least eukaryotic homology, and be accessible to antibiotics4. Since the discovery of bacterial cytoskeletal proteins involved in cell division and cell shape maintenance, they have emerged as a promising focal point for developing antibacterial compounds5. These proteins are essential for bacterial viability and play a pivotal role in maintaining cell shape (MreB, CreS), division (FtsZ, FtsA), and DNA segregation (ParM, TubZ, PhuZ, AlfA), akin to the cytoskeleton in eukaryotic cells. Notably, FtsZ exhibits a remarkably high level of conservation across a wide range of prokaryotic organisms, while MreB is found in nearly all rod-shaped bacteria. Such wide distribution and relevance in cell viability make these proteins a fascinating target in antibiotic research5,6,7.
It is crucial to adopt a multi-pronged approach that combines in vivo observations, in vitro interactions, and enzymatic experiments to thoroughly validate bacterial cytoskeleton proteins as the primary target of a potential inhibitor7. Laborious procedures or substantial cost implications encumber many available assays for this purpose. These are notable obstacles to their widespread utilization in screening lead compounds that could impact the bacterial cytoskeleton. Among these, microscopy stands out as an exceptionally efficient and rapid method for assessing the effectiveness of compounds by directly examining changes in cell morphology. Yet, the hetero-association of target protein with other cytoskeleton complexes, indirect effects due to off-target binding and changes in membrane potential, difficulty in penetrating the cell efficiently, and presence of efflux pumps, especially in Gram-negative bacteria, make it collectively complex to pinpoint the precise cause of bacterial cell deformation8,9,10.
Schizosaccharomyces pombe, or fission yeast as it&#39;s commonly known, is a rod-shaped unicellular eukaryotic organism. Fission yeast is widely used as a model organism in cellular and molecular biology due to the extraordinary conservation in cellular processes such as the cell cycle and division, cellular organization, and chromosome replication with higher eukaryotes, including humans11,12. Furthermore, Errington and colleagues expressed a pole-localized bacterial cytoskeletal protein DivIVA in fission yeast to demonstrate that DivIVA accumulated on negatively curved surfaces13. Again, Balasubramanian and group had first established fission yeast as a cellular model system to bring new insights into the mechanism, assembly, and dynamicity of the E. coli actin cytoskeleton protein like MreB14 and tubulin homolog FtsZ15. They also demonstrate the ability of A22 to efficiently impede the polymerization of MreB through epifluorescence microscopy when expressed in yeast14. Following this, other groups have also successfully employed fission yeast to study the assembly properties of chloroplast FtsZ1 and FtsZ2 proteins16. More recently, we have established a proof-of-concept of the viability of the use of fission yeast as a cellular platform to specifically screen for bacterial cytoskeleton inhibitors by conducting a comprehensive assessment of the impact of three known FtsZ inhibitors-sanguinarine, berberine, and PC190723-on FtsZ proteins derived from two pathogenic bacteria, namely Staphylococcus aureus and Helicobacter pylori17. Additionally, this single-step cell-based assay proves instrumental in minimizing the risk of identifying compounds that may be potentially toxic to eukaryotic cells.
In this report, utilizing the fission yeast system, we propose a systematic workflow using the standard 96-well plate for semi-automated screening and quantification of the effect of small molecule inhibitors targeting FtsZ from Staphylococcus aureus and MreB from Escherichia coli. Here, we set up and optimize the semi-automated workflow using the established inhibitors PC190723 and A22 that specifically target FtsZ and MreB, respectively. This workflow uses an epifluorescence microscope equipped with a motorized high-precision stage and automated image acquisition in a standard 96-well plate to improve upon current standardization. Hence, it can be applied to medium- as well as high-throughput screens of synthetic chemical libraries and circumvents some of the challenges listed above.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>96 Well CC2 Optical CVG Sterile, w/Lid. Black</td>
			<td>Thermo Scientific&#8482;</td>
			<td>160376</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well plate</td>
			<td>Corning&#160;</td>
			<td>&#160;CLS3370</td>
			<td></td>
		</tr>
		<tr>
			<td>A22 Hydrochloride</td>
			<td>Sigma&#160;</td>
			<td>SML0471</td>
			<td>Dissolved in DMSO</td>
		</tr>
		<tr>
			<td>Adenine</td>
			<td>FormediumTM</td>
			<td>DOC0229</td>
			<td>225 mg/L of media&#160;</td>
		</tr>
		<tr>
			<td>Concanavalin A&#160;</td>
			<td>Sigma&#160;</td>
			<td>C5275-5MG</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Sigma&#160;</td>
			<td>317275</td>
			<td></td>
		</tr>
		<tr>
			<td>Edinburg minimal medium (EMM Agar or EMM Broth)</td>
			<td>FormediumTM</td>
			<td>PMD0210</td>
			<td>See below for composition</td>
		</tr>
		<tr>
			<td>EDTA&#160;</td>
			<td>Sigma&#160;</td>
			<td>EDS-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>epMotion&#174; 96 with 2-position slider</td>
			<td>Eppendorf</td>
			<td>5069000101</td>
			<td></td>
		</tr>
		<tr>
			<td>Histidine</td>
			<td>FormediumTM</td>
			<td>DOC0144</td>
			<td>225 mg/L of media&#160;</td>
		</tr>
		<tr>
			<td>Leica DMi8 inverted fluorescence microscope</td>
			<td>Leica Microsystems</td>
			<td></td>
			<td>German company</td>
		</tr>
		<tr>
			<td>Leucine</td>
			<td>FormediumTM</td>
			<td>DOC0157</td>
			<td>225 mg/L of media&#160;</td>
		</tr>
		<tr>
			<td>Lithium acetate&#160;</td>
			<td>Sigma&#160;</td>
			<td>517992-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>PC190723</td>
			<td>Merck&#160;</td>
			<td>344580</td>
			<td>Dissolved in DMSO</td>
		</tr>
		<tr>
			<td>Polyethylene glycol (PEG)</td>
			<td>Sigma&#160;</td>
			<td>202398</td>
			<td></td>
		</tr>
		<tr>
			<td>Thiamine</td>
			<td>Sigma</td>
			<td>T4625</td>
			<td>Filter sterilised</td>
		</tr>
		<tr>
			<td>Tris-Hydrochloride</td>
			<td>MP</td>
			<td>194855</td>
			<td></td>
		</tr>
		<tr>
			<td>Uracil</td>
			<td>FormediumTM</td>
			<td>DOC0214</td>
			<td>225 mg/L of media, Store solution at 36&#176;C</td>
		</tr>
		<tr>
			<td>YES (Yeast extract + supplements) Agar</td>
			<td>FormediumTM</td>
			<td>PCM0410</td>
			<td>See below for composition</td>
		</tr>
		<tr>
			<td>YES (Yeast extract + supplements) Broth</td>
			<td>FormediumTM</td>
			<td>PCM0310</td>
			<td>See below for composition</td>
		</tr>
		<tr>
			<td>Yeast (S. pombe) media&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Yeast extract + supplements (YES)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Composition</td>
			<td>g/L</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Yeast extract</td>
			<td>5</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Dextrose</td>
			<td>30</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Agar</td>
			<td>17</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Adenine</td>
			<td>0.05</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>L-Histidine</td>
			<td>0.05</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>L-Leucine</td>
			<td>0.05</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>L-Lysine HCl</td>
			<td>0.05</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Uracil</td>
			<td>0.05</td>
			<td></td>
		</tr>
		<tr>
			<td>Edinburg minimal medium (EMM)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Composition</td>
			<td>g/L</td>
			<td>concentration</td>
		</tr>
		<tr>
			<td></td>
			<td>potassium hydrogen phthallate&#160;</td>
			<td>3</td>
			<td>14.7mM</td>
		</tr>
		<tr>
			<td></td>
			<td>Na2HPO4&#160;</td>
			<td>2.2</td>
			<td>15.5 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>NH4Cl&#160;</td>
			<td>5</td>
			<td>93.5 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>glucose</td>
			<td>2% (w/v) or 20 g/L</td>
			<td>&#160;111 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>Salts (stock x 50)</td>
			<td>20 mL/L (v/v)</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Vitamins (stock x 1000)</td>
			<td>1 mL/L (v/v)</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Minerals (Stock x 10,000)</td>
			<td>0.1 mL/L (v/v)</td>
			<td></td>
		</tr>
		<tr>
			<td>Salts x 50&#160;</td>
			<td>52.5 g/l MgCl2.6H20 (0.26 M)&#160;</td>
			<td>52.5</td>
			<td>0.26 M</td>
		</tr>
		<tr>
			<td></td>
			<td>0.735 mg/l CaCl2.2H20 (4.99 mM)&#160;</td>
			<td>0.000735</td>
			<td>4.99 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>50 g/l KCl (0.67 M)&#160;</td>
			<td>50</td>
			<td>0.67 M</td>
		</tr>
		<tr>
			<td></td>
			<td>2 g/l Na2SO4 (14.l mM)</td>
			<td>2</td>
			<td>14.1 mM</td>
		</tr>
		<tr>
			<td>Vitamins x 1000&#160;</td>
			<td>1 g/l pantothenic acid&#160;</td>
			<td>1</td>
			<td>4.20 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>10 g/l nicotinic acid&#160;</td>
			<td>10</td>
			<td>81.2 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>10 g/l inositol&#160;</td>
			<td>10</td>
			<td>55.5 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>10 mg/l biotin&#160;</td>
			<td>0.01</td>
			<td>40.8 &#181;M</td>
		</tr>
		<tr>
			<td>Minerals x 10,000&#160;</td>
			<td>boric acid</td>
			<td>5</td>
			<td>80.9 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>MnSO4&#160;&#160;</td>
			<td>4</td>
			<td>23.7 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>ZnSO4.7H2O</td>
			<td>4</td>
			<td>13.9 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>FeCl2.6H2O&#160;&#160;</td>
			<td>2</td>
			<td>7.40 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>molybdic acid&#160;</td>
			<td>0.4</td>
			<td>2.47 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>KI&#160;</td>
			<td>1</td>
			<td>6.02 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>CuSO4.5H2O&#160;</td>
			<td>0.4</td>
			<td>1.60 mM</td>
		</tr>
		<tr>
			<td></td>
			<td>citric acid&#160;</td>
			<td>10</td>
			<td>47.6 mM</td>
		</tr>
		<tr>
			<td>Strains/ Plasmids</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Strains</td>
			<td>Description</td>
			<td>Reference</td>
			<td></td>
		</tr>
		<tr>
			<td>CCD190</td>
			<td>Escherichia coli DH10&#946;&#160;</td>
			<td>Invitrogen</td>
			<td></td>
		</tr>
		<tr>
			<td>CCDY4&#160;</td>
			<td>MBY3532; CCDY346/pREP42- GFP-EcMreB</td>
			<td>Srinivasan et al., 2007</td>
			<td></td>
		</tr>
		<tr>
			<td>CCDY340</td>
			<td>CCDY346/pREP42- SaFtsZ-GFP</td>
			<td>Sharma et al., 2023</td>
			<td></td>
		</tr>
		<tr>
			<td>CCDY346</td>
			<td>MBY192; Schizosaccharomyces pombe [ura4-D18, leu1-32, h-]</td>
			<td>Dr. Mithilesh Mishra (DBS, TIFR)</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasmids</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pCCD3</td>
			<td>pREP42-GFP-EcMreB</td>
			<td>Srinivasan et al., 2007</td>
			<td></td>
		</tr>
		<tr>
			<td>pCCD713</td>
			<td>pREP42-SaFtsZ-GFP</td>
			<td>Sharma et al., 2023</td>
			<td></td>
		</tr>
	</tbody>
</table>

fission yeast as a platform for antibacterial drug screens targeting bacterial cytoskeleton proteins

Bacterial cytoskeletal proteins such as FtsZ and MreB perform essential functions such as cell division and cell shape maintenance. Further, FtsZ and MreB have emerged as important targets for novel antimicrobial discovery. Several assays have been developed to identify compounds targeting nucleotide binding and polymerization of these cytoskeletal proteins, primarily focused on FtsZ. Moreover, many of the assays are either laborious or cost-intensive, and ascertaining whether these proteins are the cellular target of the drug often requires multiple methods. Finally, the toxicity of the drugs to eukaryotic cells also poses a problem. Here, we describe a single-step cell-based assay to discover novel molecules targeting bacterial cytoskeleton and minimize hits that might be potentially toxic to eukaryotic cells. Fission yeast is amenable to high-throughput screens based on microscopy, and a visual screen can easily identify any molecule that alters the polymerization of FtsZ or MreB. Our assay utilizes the standard 96-well plate and relies on the ability of the bacterial cytoskeletal proteins to polymerize in a eukaryotic cell such as the fission yeast. While the protocols described here are for fission yeast and utilize FtsZ from Staphylococcus aureus and MreB from Escherichia coli, they are easily adaptable to other bacterial cytoskeletal proteins that readily assemble into polymers in any eukaryotic expression hosts. The method described here should help facilitate further discovery of novel antimicrobials targeting bacterial cytoskeletal proteins.

Author Spotlight: Exploring Cytoskeletal Dynamics to Unveil Novel Antibiotics Through Innovative Cell-Based Assays

Fission Yeast as a Platform for Antibacterial Drug Screens Targeting Bacterial Cytoskeleton Proteins

Our laboratory is interested in understanding how cytoskeletal proteins assemble dynamic structures to regulate functions such as DNA partitioning and cell division in bacteria. We are also interested in discovering compounds that target these cytoskeletal proteins to develop novel antibiotics. Our protocol is a cell-based assay in which the bacterial cytoskeleton protein polymerizes in a molecularly crowded environment in the eukaryotic yeast, Schizosaccharomyces pombe.With this approach, simultaneously, we can identify molecules that directly affects the bacterial cytoskeleton proteins, polymerization, and are potentially toxic. Using this fission yeast platform, we plan to screen libraries of macrocyclic compounds, specifically targeting FtsZ of pathogenic bacteria like Helicobacter pylori and Pseudomonas aeruginosa. We also plan to expand the screens to target actin-like proteins from Clostridium perfringens involved in plasmid segregation.

Setting up the 96-well plate for the screening of drugs 
Use of S. pombe to express a C- terminally GFP tagged S. aureus FtsZ from a vector (pREP42) containing the medium-strength thiamine repressible promoter nmt41has been previously established17 and similarly, the E. coli MreB tagged with N- terminal GFP was also expressed in S. pombe14. We have also shown that PC190723, a specific inhibitor of SaFtsZ and...

Read this Scientific Article Protocol about Author Spotlight: Exploring Cytoskeletal Dynamics to Unveil Novel Antibiotics Through Innovative Cell-Based Assays at JoVE.com

Fission yeast is used here as a heterologous host to express bacterial cytoskeletal proteins such as FtsZ and MreB as translational fusion proteins with GFP to visualize their polymerization. Also, compounds that affect polymerization are identified by imaging using a fluorescence microscope.

Bacterial cytoskeletal proteins such as FtsZ and MreB perform essential functions such as cell division and cell shape maintenance. Further, FtsZ and MreB ...

fission-yeast-as-platform-for-antibacterial-drug-screens-targeting

Research

JoVE Journal

Biology

Targeting GFP-Tagged Bacterial Cytoskeletal Proteins Expressed in Schizosaccharomyces pombe and Microscopic Imaging of the Polymers

552 Views.  National Institute of Science Education and Research.  Fission yeast is used here as a heterologous host to express bacterial cytoskeletal proteins such as FtsZ and MreB as translational fusion proteins with GFP to visualize their polymerization. Also, compounds that affect polymerization are identified by imaging using a fluorescence microscope.

Identifying Drugs that Affect Polymerization of Bacterial Cytoskeletal Proteins

Summary