The Tol proteins of Escherichia coli and their involvement in the uptake of biomolecules and outer membrane stability

Lazzaroni, Jean-Claude

doi:10.1016/s0378-1097(99)00293-1

Cited by 62 publications

(83 citation statements)

References 25 publications

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“…Unlike TonB, which interacts with the Ton-boxcontaining OM receptors, the C-terminal domain of TolA interacts with a periplasmic protein, TolB, or the OM lipoprotein PAL (384). Defects in any of the TolQR-TolB system components result in profound functional problems with the OM barrier, increasing drastically the formation of OM vesicles (see below), causing periplasmic proteins (such as RNase and ␤-lactamase) to leak out of the cell, and making the cells hypersusceptible to various noxious agents (367). The hypersusceptibility pattern is interesting in that it includes not only lipophilic agents expected to traverse the OM bilayer (such as SDS and cholate) (367) but also vancomycin (119), which is large but hydrophilic, so that it does not cross the OM unless large, supramolecular defects open up.…”

Section: Alterations Of the Om Bilayer Barriermentioning

confidence: 99%

Molecular Basis of Bacterial Outer Membrane Permeability Revisited

Nikaido

2003

Microbiol Mol Biol Rev

3,839

3,800

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Gram-negative bacteria characteristically are surrounded by an additional membrane layer, the outer membrane. Although outer membrane components often play important roles in the interaction of symbiotic or pathogenic bacteria with their host organisms, the major role of this membrane must usually be to serve as a permeability barrier to prevent the entry of noxious compounds and at the same time to allow the influx of nutrient molecules. This review summarizes the development in the field since our previous review (H. Nikaido and M. Vaara, Microbiol. Rev. 49:1-32, 1985) was published. With the discovery of protein channels, structural knowledge enables us to understand in molecular detail how porins, specific channels, TonB-linked receptors, and other proteins function. We are now beginning to see how the export of large proteins occurs across the outer membrane. With our knowledge of the lipopolysaccharide-phospholipid asymmetric bilayer of the outer membrane, we are finally beginning to understand how this bilayer can retard the entry of lipophilic compounds, owing to our increasing knowledge about the chemistry of lipopolysaccharide from diverse organisms and the way in which lipopolysaccharide structure is modified by environmental conditions

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Section: Alterations Of the Om Bilayer Barriermentioning

confidence: 99%

Molecular Basis of Bacterial Outer Membrane Permeability Revisited

Nikaido

2003

Microbiol Mol Biol Rev

3,839

3,800

View full text Add to dashboard Cite

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“…This system has also been found to facilitate the uptake of filamentous phage DNA and group A colicins. No obvious phenotypes have been assigned to ybgC and ybgF, which encode cytoplasmic and periplasmic proteins, respectively (Lazzaroni et al, 1999;Cascales & Lloubes, 2004). Recently, it has been shown that the TolA protein is required for the correct surface expression of the E. coli O7 antigen, thus demonstrating a role of the Tol-Pal system in LPS Fig.…”

Section: Members Of the S E Regulon Specific For S Typhimuriummentioning

confidence: 99%

Identification of the σ E regulon of Salmonella enterica serovar Typhimurium

et al. 2006

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The extracytoplasmic function sigma factor, s E , has been shown to play a critical role in virulence of Salmonella enterica serovar Typhimurium (S. Typhimurium). The previously optimized two-plasmid system has been used to identify S. Typhimurium promoters recognized by RNA polymerase containing s E . This method allowed identification of 34 s E -dependent promoters that direct expression of 62 genes in S. Typhimurium, 23 of which (including several specific for S. Typhimurium) have not been identified previously to be dependent upon s E in Escherichia coli. The promoters were confirmed in S. Typhimurium and transcriptional start points of the promoters were determined by S1-nuclease mapping. All the promoters contained sequences highly similar to the consensus sequence of s E -dependent promoters. The identified genes belonging to the S.Typhimurium s E -regulon encode proteins involved in primary metabolism, DNA repair systems and outer-membrane biogenesis, and regulatory proteins, periplasmic proteases and folding factors, proposed lipoproteins, and inner-and outer-membrane proteins with unknown functions. Several of these s E -dependent genes have been shown to play a role in virulence of S. Typhimurium.

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“…The Tol-Pal system of Gram-negative bacteria is required for outer-membrane stability (Lazzaroni et al, 1999). It comprises five envelope proteins, TolQ, TolR, TolA, TolB and Pal, which form two complexes.…”

Section: Introductionmentioning

confidence: 99%

Tol-Pal proteins are critical cell envelope components of Erwinia chrysanthemi affecting cell morphology and virulence

Dubuisson

Vianney

Hugouvieux‐Cotte‐Pattat

et al. 2005

Microbiology

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The tol-pal genes are necessary for maintaining the outer-membrane integrity of Gram-negative bacteria. These genes were first described in Escherichia coli, and more recently in several other species. They are involved in the pathogenesis of E. coli, Haemophilus ducreyi, Vibrio cholerae and Salmonella enterica. The role of the tol-pal genes in bacterial pathogenesis was investigated in the phytopathogenic enterobacterium Erwinia chrysanthemi, assuming that this organism might be a good model for such a study. The whole Er. chrysanthemi tol-pal region was characterized. Tol-Pal proteins, except TolA, showed high identity scores with their E. coli homologues. Er. chrysanthemi mutants were constructed by introducing a uidA-kan cassette in the ybgC, tolQ, tolA, tolB, pal and ybgF genes. All the mutants were hypersensitive to bile salts. Mutations in tolQ, tolA, tolB and pal were deleterious for the bacteria, which required high concentrations of sugars or osmoprotectants for their viability. Consistent with this observation, they were greatly impaired in their cell morphology and division, which was evidenced by observations of cell filaments, spherical forms, membrane blebbing and mislocalized bacterial septa. Moreover, tol-pal mutants showed a reduced virulence in a potato tuber model and on chicory leaves. This could be explained by a combination of impaired phenotypes in the tol-pal mutants, such as reduced growth and motility and a decreased production of pectate lyases, the major virulence factor of Er. chrysanthemi. INTRODUCTIONThe Tol-Pal system of Gram-negative bacteria is required for outer-membrane stability (Lazzaroni et al., 1999). It comprises five envelope proteins, TolQ, TolR, TolA, TolB and Pal, which form two complexes. The TolQ, TolR and TolA inner-membrane proteins interact via their transmembrane domains (Derouiche et al., 1995;Lazzaroni et al., 1995). The b-propeller domain of the periplasmic protein TolB is responsible for its interaction with Pal (Ray et al., 2000). TolB also interacts with the outer-membrane peptidoglycan-associated proteins Lpp and OmpA (Cascales et al., 2002;Clavel et al., 1998). TolA undergoes a conformational change in response to changes in the protonmotive force (Germon et al., 2001), and interacts with Pal in an energy-dependent manner (Cascales et al., 2001). The Cterminal periplasmic domain of TolA also interacts with the N-terminal domain of TolB (Dubuisson et al., 2002;Walburger et al., 2002).The transcriptional organization of the E. coli tol-pal genes has been characterized. The genes ybgC (orf1), tolQ, tolR, tolA and tolB, and pal and ybgF (orf2) form two operons (Muller & Webster, 1997); a large ybgC-ybgF transcript has also been postulated (Vianney et al., 1996). ybgC and ybgF encode proteins of unknown function located in the cytoplasm and the periplasm, respectively (Clavel et al., 1996;Sun & Webster, 1987). Inactivation of these two ORFs induces no obvious phenotype in E. coli. In contrast, mutations in the tol-pal genes cause the disruption of outermembr...

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The Tol proteins of Escherichia coli and their involvement in the uptake of biomolecules and outer membrane stability

Cited by 62 publications

References 25 publications

Molecular Basis of Bacterial Outer Membrane Permeability Revisited

Molecular Basis of Bacterial Outer Membrane Permeability Revisited

Identification of the σ E regulon of Salmonella enterica serovar Typhimurium

Tol-Pal proteins are critical cell envelope components of Erwinia chrysanthemi affecting cell morphology and virulence

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