YeeU enhances the bundling of cytoskeletal polymers of MreB and FtsZ, antagonizing the CbtA (YeeV) toxicity in Escherichia coli.
ABSTRACT All free-living bacteria carry the toxin-antitoxin (TA) systems controlling cell growth and death under stress conditions. YeeU-YeeV (CbtA) is one of the Escherichia coli TA systems, and the toxin, CbtA, has been reported to inhibit the polymerization of bacterial cytoskeletal proteins, MreB and FtsZ. Here, we demonstrate that the antitoxin, YeeU, is a novel type of antitoxin (type IV TA system), which does not form a complex with CbtA but functions as an antagonist for CbtA toxicity. Specifically, YeeU was found to directly interact with MreB and FtsZ, and enhance the bundling of their filamentous polymers in vitro. Surprisingly, YeeU neutralized not only the toxicity of CbtA but also the toxicity caused by other inhibitors of MreB and FtsZ, such as A22, SulA and MinC, indicating that YeeU-induced bundling of MreB and FtsZ has an intrinsic global stabilizing effect on their homeostasis. Here we propose to rename YeeU as CbeA for cytoskeleton bundling-enhancing factor A.
- SourceAvailable from: Sebastien Pichoff[show abstract] [hide abstract]
ABSTRACT: The min system spatially regulates division through the topological regulation of MinCD, an inhibitor of cell division. MinCD was previously shown to inhibit division by preventing assembly of the Z ring (E. Bi and J. Lutkenhaus, J. Bacteriol. 175:1118-1125, 1993); however, this was questioned in a recent report (S. S. Justice, J. Garcia-Lara, and L. I. Rothfield, Mol. Microbiol. 37:410-423, 2000) which indicated that MinCD acted after Z-ring formation and prevented the recruitment of FtsA to the Z ring. This discrepancy was due in part to alternative fixation conditions. We have therefore reinvestigated the action of MinCD and avoided fixation by using green fluorescent protein (GFP) fusions to division proteins. MinCD prevented the localization of both FtsZ-GFP and ZipA-GFP, consistent with it preventing Z-ring assembly. Consistent with a direct interaction between FtsZ and the MinCD inhibitor, we find that increased FtsZ, but not FtsA, suppresses MinCD-induced lethality. Furthermore, strains carrying various alleles of ftsZ, selected on the basis of resistance to the inhibitor SulA, displayed variable resistance to MinCD. These results are consistent with FtsZ as the target of MinCD and confirm that this inhibitor prevents Z-ring assembly.Journal of Bacteriology 12/2001; 183(22):6630-5. · 3.19 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Broad-host-range plasmid RK2 encodes a post-segregational killing system, parDE, which contributes to the stable maintenance of this plasmid in Escherichia coli and many distantly related bacteria. The ParE protein is a toxin that inhibits cell growth, causes cell filamentation and eventually cell death. The ParD protein is a specific ParE antitoxin. In this work, the in vitro activities of these two proteins were examined. The ParE protein was found to inhibit DNA synthesis using an E. coli oriC supercoiled template and a replication-proficient E. coli extract. Moreover, ParE inhibited the early stages of both chromosomal and plasmid DNA replication, as measured by the DnaB helicase- and gyrase-dependent formation of FI*, a highly unwound form of supercoiled DNA. The presence of ParD prevented these inhibitory activities of ParE. We also observed that the addition of ParE to supercoiled DNA plus gyrase alone resulted in the formation of a cleavable gyrase-DNA complex that was converted to a linear DNA form upon addition of sodium dodecyl sulphate (SDS). Adding ParD before or after the addition of ParE prevented the formation of this cleavable complex. These results demonstrate that the target of ParE toxin activity in vitro is E. coli gyrase.Molecular Microbiology 06/2002; 44(4):971-9. · 4.96 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Bacterial populations produce a small number of dormant persister cells that exhibit multidrug tolerance. All resistance mechanisms do essentially the same thing: prevent the antibiotic from hitting a target. By contrast, tolerance apparently works by shutting down the targets. Bactericidal antibiotics kill bacteria by corrupting their targets, rather than merely inhibiting them. Shutting down the targets then protects from killing. The number of persisters in a growing population of bacteria rises at mid-log and reaches a maximum of approximately 1% at stationary state. Similarly, slow-growing biofilms produce substantial numbers of persisters. The ability of a biofilm to limit the access of the immune system components, and the ability of persisters to sustain an antibiotic attack could then account for the recalcitrance of such infections in vivo and for their relapsing nature. Isolation of Escherichia coli persisters by lysing a population or by sorting GFP-expressing cells with diminished translation allowed to obtain a gene expression profile. The profile indicated downregulated biosynthetic pathways, consistent with their dormant nature, and indicated overexpression of toxin/antitoxin (TA) modules. Stochastic overexpression of toxins that inhibit essential functions such as translation may contribute to persister formation. Ectopic expression of RelE, MazF, and HipA toxins produced multidrug tolerant cells. Apart from TA modules, glpD and plsB were identified as potential persister genes by overexpression cloning of a genomic library and selection for antibiotic tolerance. Yeast Candida albicans forms recalcitrant biofilm infections that are tolerant to antibiotics, similarly to bacterial biofilms. C. albicans biofilms produce multidrug tolerant persisters that are not mutants, but rather phenotypic variants of the wild type. Unlike bacterial persisters, however, C. albicans persisters were only observed in a biofilm, but not in a planktonic stationary population. Identification of persister genes opens the way to a rational design of anti-biofilm therapy. Combination of a conventional antibiotic with a compound inhibiting persister formation or maintenance may produce an effective therapeutic. Other approaches to the problem include sterile-surface materials, prodrug antibiotics, and cyclical application of conventional antimicrobials.Current topics in microbiology and immunology 02/2008; 322:107-31. · 4.86 Impact Factor