Persister Cells
All bacterial populations stochastically produce a small number of dormant persister cells tolerant to antibiotics. Persisters are not mutants but phenotypic variants of the wild type.
We are interested in discovering the mechanism of persister formation. Using cell sorting and transcriptome analysis, we find that chromosomally-encoded "toxin" genes act to shut down cellular functions, creating a dormant state. Examples include HipA, which encodes a protein kinase that phosphorylates elongation factor Ef-Tu, blocking protein synthesis, and TisB, a small peptide that inserts in the membrane, causing a drop in pmf and ATP levels. Interestingly, TisB synthesis is induced by DNA damaging agents, including fluoroquinolone antibiotics. This means that persisters can be formed not only stochastically, but through stress response mechanisms.
We find that in chronic infections such as cystic fibrosis, antibiotic treatment selects for high-persister mutants. Whole genome sequencing indicates the mechanism for increased production of persisters.
Current projects involve the study of the molecular mechanisms of persister formation governed by HipA and TisB in E. coli; the search for persister genes in P. aeruginosa, S. aureus and M. tuberculosis; and characterization of high-persister mutants from clinical isolates of these pathogens. A related project is discovery of compounds capable of eliminating persisters. The work of the persister group is supported by a Transformative Award from the NIH, and with grants from ARO and CF Foundation.
Video courtesy of 3dcienciaMembers:
Marin VulićRon Ortenberg
Brian Conlan
Janet Manson
Lawrence R. Mulcahy
Sonja Hansen
Sarah Rowe
Yanxia Wu
Pooja Balani
Alyssa Theodore
Persister Cells Selected Publications:
Schumacher, M.A., Piro, K.M., Xu, W., Hansen, S., Lewis, K., and Brennan, R.G. (2009). Molecular Mechanisms of HipA Mediated Multidrug Tolerance and its Neutralization by HipB. Accepted in Science.
Hansen S, Lewis K, Vulić M. (2008). Role of global regulators and nucleotide metabolism in antibiotic tolerance in Escherichia coli. Antimicrob Agents Chemother. 52(8):2718-26.Lewis K. (2008).Multidrug tolerance of biofilms and persister cells. Curr Top Microbiol Immunol. 322:107-31. Review.
Lewis, K. (2007) Persister cells, dormancy and infectious disease. Nat. Rev. Microbiol. 5:48-56. [PDF]
Correia, FF., D’Onofrio, A., Rejtar, T., Li, L., Karger, BL., Makarova, K., Koonin, EV., and Lewis, K. (2006) Kinase activity of overexpressed HipA is required for growth arrest and multidrug tolerance in Escherichia coli. J. Bacteriol. 188:8360-7. [PDF]
Shah D, Zhang Z, Khodursky AB, Kaldalu N, Kurg K, Lewis K. (2006) Persisters: a distinct physiological state of E. coli. BMC Microbiology. 6:53
LaFleur, MD., Kumamoto, CA., and Lewis, K. (2006) Candida albicans biofilms produce antifungal-tolerant persister cells. Antimicrob. Agents Chemother. 50:3839-46. [PDF]
Spoering, A.L., Vulic, M., Lewis, K. (2006) GlpD and PlsB Participate in Persister Cell Formation in Escherichia coli. J. Bacteriol. 188:5136-44. [PDF]
Lewis K. (2005). Persister cells and the riddle of biofilm survival. Biochemistry. (Mosc);70(2):267-74.
Lewis, K., Spoering, A., Kaldalu, N., Keren, I., and Shah, D. (2005) Persisters: Specialized Cells Responsible For Biofilm Tolerance To Antimicrobial Agents. In Biofilms, Infection, and Antimicrobial Therapy. Pace, J., Rupp, M.E. and Finch, R.G. (eds). Boca Raton, London, New York, Singapore: Taylor & Francis, pp. 241-256.
Keren, I., Shah, D., Spoering, A., Kaldalu, N., and Lewis, K. (2004) Specialized persister cells and the mechanism of multidrug tolerance in Escherichia coli. J Bacteriol. 186:8172-80. [PDF]
Keren, I., Kaldalu, N., Spoering, A., Wang, Y., and Lewis, K. (2004). Persister cells and tolerance to antimicrobials. FEMS Microbiol. Lett. 230: 13-18. [PDF]
Kaldalu, N., Mei, R., and Lewis, K. (2004) Killing by ampicillin and ofloxacin induces overlapping changes in Escherichia coli transcription profile. Antimicrob. Agents Chemother. 48:890-896.
Spoering, A.L. and Lewis, K. (2001) Biofilms and Planktonic Cells of Pseudomonas aeruginosa Have Similar Resistance to Killing by Antimicrobials. J. Bacteriol. 183:6746-6751. [PDF]
Lewis K. (2001). Riddle of biofilm resistance. Antimicrob Agents Chemother. 45(4):999-1007.
Brooun, A., Liu, S., and Lewis, K. (2000) A Dose-Response Study of Antibiotic Resistance in Pseudomonas aeruginosa Biofilms. Antimicrob. Agents Chemother. 44:640-646. [PDF]