Affiliation:
1. Antimicrobial Discovery Center and Department of Biology, Northeastern University, Boston, Massachusetts 02115
Abstract
ABSTRACT
Bacterial populations produce a small number of persister cells that exhibit multidrug tolerance. Persister cells are largely responsible for the antibiotic recalcitrance of biofilm infections. The mechanism of persister cell formation largely remains unknown due to the challenges in identifying persister genes. We screened an ordered comprehensive library of 3,985
Escherichia coli
knockout strains to identify mutants with altered antibiotic tolerance. Stationary-state cultures in 96-well plates were exposed to ofloxacin at a concentration which allows only tolerant persister cells to survive. The persister cell level of each culture was determined. A total of 150 mutants with decreased persistence were identified in the initial screen, and subsequent validation confirmed that neither the growth rate nor the ofloxacin MIC was affected for 10 of them. The genes affected in these strains were
dnaJ
and
dnaK
(chaperones),
apaH
(diadenosine tetraphosphatase),
surA
(peptidyl-prolyl
cis
-
trans
isomerase),
fis
and
hns
(global regulators),
hnr
(response regulator of RpoS),
dksA
(transcriptional regulator of rRNA transcription),
ygfA
(5-formyl-tetrahydrofolate cyclo-ligase), and
yigB
(flavin mononucleotide [FMN] phosphatase). The prominent presence of global regulators among these strains pointed to the likely redundancy of persister cell formation mechanisms: the elimination of a regulator controlling several redundant persister genes would be expected to produce a phenotype. This observation is consistent with previous findings for a possible role of redundant genes such as toxin/antitoxin modules in persister cell formation.
ygfA
and
yigB
were of special interest. The mammalian homolog of YgfA (methenyltetrahydrofolate synthetase) catalyzes the conversion of 5-formyl-tetrahydrofolate (THF) into the rapidly degraded 5,10-methenyl-THF, depleting the folate pool. The YigB protein is a phosphatase of FMN which would deplete the pool of this cofactor. Stochastic overexpression of these genes could lead to dormancy and, hence, tolerance by depleting the folate and FMN pools, respectively. Consistent with this scenario, the overexpression of both genes produced increased tolerance to ofloxacin.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Reference67 articles.
1. Determination of minimum inhibitory concentrations
2. Anguera, M. C., J. R. Suh, H. Ghandour, I. M. Nasrallah, J. Selhub, and P. J. Stover. 2003. Methenyltetrahydrofolate synthetase regulates folate turnover and accumulation. J. Biol. Chem.278:29856-29862.
3. Arfin, S. M., A. D. Long, E. T. Ito, L. Tolleri, M. M. Riehle, E. S. Paegle, and G. W. Hatfield. 2000. Global gene expression profiling in Escherichia coli K12. The effects of integration host factor. J. Biol. Chem.275:29672-29684.
4. Construction of
Escherichia coli
K‐12 in‐frame, single‐gene knockout mutants: the Keio collection
5. Baba, T., T. Ara, M. Hasegawa, Y. Takai, Y. Okumura, M. Baba, K. A. Datsenko, M. Tomita, B. L. Wanner, and H. Mori. 2006. Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection. Mol. Systems Biol2:1-11.
Cited by
259 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献