PMID:19806199

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Citation

Glover, WA, Yang, Y and Zhang, Y (2009) Insights into the molecular basis of L-form formation and survival in Escherichia coli. PLoS ONE 4:e7316

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.

Links

PubMed PMC2752164 Online version:10.1371/journal.pone.0007316

Keywords

Anti-Bacterial Agents/pharmacology; Escherichia coli/metabolism; Escherichia coli/physiology; Escherichia coli Proteins/chemistry; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Genome; Models, Biological; Mutation; Oligonucleotide Array Sequence Analysis; Organic Chemicals/pharmacology; Reverse Transcriptase Polymerase Chain Reaction

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