New Insights into the Lpt Machinery for Lipopolysaccharide Transport to the Cell Surface: LptA-LptC Interaction and LptA Stability as Sensors of a Properly Assembled Transenvelope Complex

Sperandeo, Paola; Villa, Riccardo; Martorana, Alessandra M.; Šamalíková, Mária; Grandori, Rita; Dehò, Gianni; Polissi, Alessandra

doi:10.1128/jb.01037-10

Cited by 84 publications

(133 citation statements)

References 43 publications

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“…The Tn5 insertion in the RSc0411 mutant is projected to result in a truncated RSc0411 protein (Fig. S1) similar to a non-functional truncated protein of E. coli LptC that is highly unstable and fails to interact with LptA, leading to LptA destabilization and impaired LPS transport (Sperandeo et al, 2011). Our results demonstrate that RSc0411 mutation is responsible for various LPS-related defects of the mutant, including increased membrane permeability, reduced level of R-LPS production, biofilm formation and root attachment.…”

Section: Discussionmentioning

confidence: 82%

“…In addition, previously Sperandeo et al (2011) proposed that LptA binds to the C-terminal region of LptC. They showed that a mutated form of LptC (LptCG153R) conferred reduced affinity to LptA and that a truncated LptC (LptC177-191), lacking the second disordered region at the C-terminal region (Fig.…”

Section: Specificity In Duf1239 Proteins Interactions With Their Intementioning

confidence: 99%

“…S1, available in Microbiology Online) was avirulent in both tomato and Arabidopsis. ubiquitous eubacterial proteins mostly not characterized, except for the E. coli DUF1239 protein LptC, which is involved in LPS transport from the IM to the OM (Sperandeo et al, 2011). The objective of this study was to determine how RSc0411 inactivation affects R. solanacearum-plant interaction and therefore bacterial pathogenesis.…”

Section: Introductionmentioning

confidence: 99%

“…Rough (R-)LPS are composed of the hydrophobic membrane-anchored lipid A moiety and the short core oligosaccharide, and the addition of variable O-antigen polysaccharide chain onto R-LPS leads to the formation of the complete structure of smooth (S-)LPS. The synthesis, assembly and transport of LPS components are well studied in Escherichia coli (Raetz & Whitfield, 2002;Wang & Quinn, 2010;Sperandeo et al, 2011). R-LPS are synthesized via a conserved pathway, which involves proteins on the cytoplasmic surface of the inner membrane (IM), then transported by MsbA across the IM where ligation of R-LPS to O-antigen is triggered by WaaL to form S-LPS.…”

Section: Introductionmentioning

confidence: 99%

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Ralstonia solanacearum RSc0411 (lptC) is a determinant for full virulence and has a strain-specific novel function in the T3SS activity

et al. 2013

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Previously, we have identified an avirulent Ralstonia solanacearum mutant carrying a transposon insertion in RSc0411, a gene homologous to the Escherichia coli LPS-transporting protein LptC. However, how the disruption of RSc0411 affects the bacterium-plant interactions and leads to decreased pathogenicity was not known. Here we show that the disruption of RSc0411 leads to pleiotropic defects, including reducing bacterial motility, biofilm formation, root attachment, roughform LPS production and virulence in tomato and increasing membrane permeability. Disruption of the orthologous RSc0411 present in other R. solanacearum strains proves that most of these functions are conserved in the species. In contrast, trans-complementation analyses show that only RSc0411 orthologues from closely related bacteria can rescue the defects of the disruption mutant. These results enable us to propose a function for RSc0411, and for the clustered genes, in LPS biogenesis, and for the first time, to our knowledge, also a role of a gene from the DUF1239 gene family in bacterial pathogenicity. In addition and notably, the RSc0411 mutant displays a strain-specific phenotype for hypersensitive response (HR), in which the RSc0411 disruption impairs the HR caused by strain Pss190 but not that by strain Pss1308. Consistent with this strain-specific defect, the mutation clearly affects expression of the type III secretion system (T3SS) in Pss190 but not in other strains, suggesting that the HR-deficient phenotype of the RSc0411 mutant in Pss190 is due to impairment of the T3SS and thus RSc0411 has a strainspecific role in the T3SS activity of R. solanacearum.

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Section: Discussionmentioning

confidence: 82%

Section: Specificity In Duf1239 Proteins Interactions With Their Intementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ralstonia solanacearum RSc0411 (lptC) is a determinant for full virulence and has a strain-specific novel function in the T3SS activity

et al. 2013

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“…1A). LptB/F/G form an ABC transporter that is believed to extract LPS from the IM (18)(19)(20); LptC associates with LptB/F/G and periplasmic LptA (21,22); and LptD/E form a complex at the OM (23)(24)(25). All Lpt factors are required for LPS transport and viability in E. coli (19,20,24,26), and they form a transenvelope protein bridge that is thought to mediate transport of LPS from the IM to the OM (27,28).…”

mentioning

confidence: 99%

Regulation of cell size in response to nutrient availability by fatty acid biosynthesis in Escherichia coli

Yao

Davis

Kishony³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

157

191

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Cell size varies greatly among different types of cells, but the range in size that a specific cell type can reach is limited. A longstanding question in biology is how cells control their size. Escherichia coli adjusts size and growth rate according to the availability of nutrients so that it grows larger and faster in nutrient-rich media than in nutrient-poor media. Here, we describe how, using classical genetics, we have isolated a remarkably small E. coli mutant that has undergone a 70% reduction in cell volume with respect to wild type. This mutant lacks FabH, an enzyme involved in fatty acid biosynthesis that previously was thought to be essential for the viability of E. coli. We demonstrate that although FabH is not essential in wild-type E. coli, it is essential in cells that are defective in the production of the small-molecule and global regulator ppGpp. Furthermore, we have found that the loss of FabH causes a reduction in the rate of envelope growth and renders cells unable to regulate cell size properly in response to nutrient excess. Therefore we propose a model in which fatty acid biosynthesis plays a central role in regulating the size of E. coli cells in response to nutrient availability.acteria regulate their size and growth rate in response to nutrient availability. For example, Escherichia coli, Salmonella typhimurium, and Bacillus subtilis cells grow larger and faster in nutrient-rich medium than in nutrient-poor medium (1-6). Changes in temperature can alter growth rate but not size (2). Therefore, the size a cell attains depends on the nutritional composition of the growth medium, suggesting that nutrients affect a rate-limiting step(s) that controls size and the rate of growth.Bacteria must coordinate cell size, growth rate, and division in response to nutrient availability. Indeed, when E. coli changes its size, it also changes its generation time inversely; however, it maintains the cell mass-to-DNA ratio constant because it initiates DNA replication whenever it reaches a particular cell mass or a multiple of that mass (6). Interestingly, recent studies have shown that B. subtilis and E. coli use different regulatory mechanisms to couple cell size and DNA replication (4, 7). In E. coli DNA replication is not initiated until the cell reaches an appropriate size, but size does not affect the timing of replication in B. subtilis. Nevertheless, the amount of active DnaA, which unwinds DNA at the origin and thereby triggers replication (8, 9), is relevant in controlling the initiation of replication in both bacteria (7). Furthermore, a metabolic pathway for glucolipid biosynthesis regulates cell size in B. subtilis in response to nutrients under conditions that promote rapid growth (4). In this pathway, the UDP-glucose transferase UgtP inhibits the assembly of the divisome, the division machinery. The levels and localization of UgtP vary with nutrient availability so that assembly of the divisome is delayed under nutrient-rich conditions, resulting in longer cells.We do not understand how nu...

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Inhibition of Lipopolysaccharide Transport to the Outer Membrane in Pseudomonas aeruginosa by Peptidomimetic Antibiotics

et al. 2012

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The asymmetric outer membrane (OM) of Gram‐negative bacteria contains lipopolysaccharide (LPS) in the outer leaflet and phospholipid in the inner leaflet. During OM biogenesis, LPS is transported from the periplasm into the outer leaflet by a complex comprising the OM proteins LptD and LptE. Recently, a new family of macrocyclic peptidomimetic antibiotics that interact with LptD of the opportunistic human pathogen Pseudomonas aeruginosa was discovered. Here we provide evidence that the peptidomimetics inhibit the LPS transport function of LptD. One approach to monitor LPS transport involved studies of lipid A modifications. Some modifications occur only in the inner membrane while others occur only in the OM, and thus provide markers for LPS transport within the bacterial envelope. We prepared a conditional lptD mutant of P. aeruginosa PAO1 that allowed control of lptD expression from the rhamnose promoter. With this mutant, the effects caused by the antibiotic on the wild‐type strain were compared with those caused by depleting LptD in the mutant strain. When LptD was depleted in the mutant, electron microscopy revealed accumulation of membrane‐like material within cells and OM blebbing; this mirrored similar effects in the wild‐type strain caused by the antibiotic. Moreover, the bacterium responded to the antibiotic, and to depletion of LptD, by introducing the same lipid A modifications, consistent with inhibition by the antibiotic of LptD‐mediated LPS transport. This conclusion was further supported by monitoring the radiolabelling of LPS from [14C]acetate, and by fractionation of IM and OM components. Overall, the results provide support for a mechanism of action for the peptidomimetic antibiotics that involves inhibition of LPS transport to the cell surface.

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New Insights into the Lpt Machinery for Lipopolysaccharide Transport to the Cell Surface: LptA-LptC Interaction and LptA Stability as Sensors of a Properly Assembled Transenvelope Complex

Cited by 84 publications

References 43 publications

Ralstonia solanacearum RSc0411 (lptC) is a determinant for full virulence and has a strain-specific novel function in the T3SS activity

Ralstonia solanacearum RSc0411 (lptC) is a determinant for full virulence and has a strain-specific novel function in the T3SS activity

Regulation of cell size in response to nutrient availability by fatty acid biosynthesis in Escherichia coli

Inhibition of Lipopolysaccharide Transport to the Outer Membrane in Pseudomonas aeruginosa by Peptidomimetic Antibiotics

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