Format

Send to

Choose Destination
PLoS One. 2009 Oct 6;4(10):e7316. doi: 10.1371/journal.pone.0007316.

Insights into the molecular basis of L-form formation and survival in Escherichia coli.

Author information

1
Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America.

Abstract

L-forms have been shown to occur among many species of bacteria and are suspected to be involved in persistent infections. Since their discovery in 1935, numerous studies characterizing L-form morphology, growth, and pathogenic potential have been conducted. However, the molecular mechanisms underlying the formation and survival of L-forms remain unknown. Using unstable L-form colonies of Escherichia coli as a model, we performed genome-wide transcriptome analysis and screened a deletion mutant library to study the molecular mechanisms involved in formation and survival of L-forms. Microarray analysis of L-form versus classical colonies revealed many up-regulated genes of unknown function as well as multiple over-expressed stress pathways shared in common with persister cells and biofilms. Mutant screens identified three groups of mutants which displayed varying degrees of defects in L-form colony formation. Group 1 mutants, which showed the strongest defect in L-form colony formation, belonged to pathways involved in cell envelope stress, DNA repair, iron homeostasis, outer membrane biogenesis, and drug efflux/ABC transporters. Four (Group 1) mutants, rcsB, a positive response regulator of colanic acid capsule synthesis, ruvA, a recombinational junction binding protein, fur, a ferric uptake regulator and smpA a small membrane lipoprotein were selected for complementation. Complementation of the mutants using a high-copy overexpression vector failed, while utilization of a low-copy inducible vector successfully restored L-form formation. This work represents the first systematic genetic evaluation of genes and pathways involved in the formation and survival of unstable L-form bacteria. Our findings provide new insights into the molecular mechanisms underlying L-form formation and survival and have implications for understanding the emergence of antibiotic resistance, bacterial persistence and latent infections and designing novel drugs and vaccines.

PMID:
19806199
PMCID:
PMC2752164
DOI:
10.1371/journal.pone.0007316
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Public Library of Science Icon for PubMed Central
Loading ...
Support Center