Identification and characterization of three novel EsaI/EsaR quorum‐sensing controlled stewartan exopolysaccharide biosynthetic genes in <i>Pantoea stewartii</i> ssp<i>. stewartii</i>

Carlier, Aurélien; Burbank, Lindsey; Bodman, Susanne B. von

doi:10.1111/j.1365-2958.2009.06906.x

Cited by 31 publications

(36 citation statements)

References 48 publications

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“…A deletion mutant of B. cenocepacia H111 cepI was created using a modified version of the Gateway method described by Choi and Schweizer [30] and modified by Carlier et al [31]. Briefly, the flanking regions of the cepI gene were amplified by PCR using oligonucleotide primers cepIDnkan, cepIDnGW, cepIUpGW and cepIUpkan listed in Table S5.…”

Section: Methodsmentioning

confidence: 99%

The AHL- and BDSF-Dependent Quorum Sensing Systems Control Specific and Overlapping Sets of Genes in Burkholderia cenocepacia H111

Schmid¹,

Pessi²,

Deng³

et al. 2012

PLoS ONE

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Quorum sensing in Burkholderia cenocepacia H111 involves two signalling systems that depend on different signal molecules, namely N-acyl homoserine lactones (AHLs) and the diffusible signal factor cis-2-dodecenoic acid (BDSF). Previous studies have shown that AHLs and BDSF control similar phenotypic traits, including biofilm formation, proteolytic activity and pathogenicity. In this study we mapped the BDSF stimulon by RNA-Seq and shotgun proteomics analysis. We demonstrate that a set of the identified BDSF-regulated genes or proteins are also controlled by AHLs, suggesting that the two regulons partially overlap. The detailed analysis of two mutually regulated operons, one encoding three lectins and the other one encoding the large surface protein BapA and its type I secretion machinery, revealed that both AHLs and BDSF are required for full expression, suggesting that the two signalling systems operate in parallel. In accordance with this, we show that both AHLs and BDSF are required for biofilm formation and protease production.

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Section: Methodsmentioning

confidence: 99%

The AHL- and BDSF-Dependent Quorum Sensing Systems Control Specific and Overlapping Sets of Genes in Burkholderia cenocepacia H111

Schmid¹,

Pessi²,

Deng³

et al. 2012

PLoS ONE

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show abstract

“…The genes encoding these two proteins, GalE (UDPgalactose-4-epimerase) and GalF (a putative regulatory subunit for GalU), are found in an operon downstream of the wceI operon needed for stewartan production (23). Another repressed protein, GalU (glucose-1-phosphate uridylyltransferase), sometimes found in a complex with GalF (24), is a limiting factor in the production of exopolysaccharide.…”

Section: Discussionmentioning

confidence: 99%

Proteomic Analysis of the Quorum-Sensing Regulon in Pantoea stewartii and Identification of Direct Targets of EsaR

Ramachandran

Stevens

2013

Appl Environ Microbiol

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The proteobacterium Pantoea stewartii subsp. stewartii causes Stewart's wilt disease in maize when it colonizes the xylem and secretes large amounts of stewartan, an exopolysaccharide. The success of disease pathogenesis lies in the timing of bacterial virulence factor expression through the different stages of infection. Regulation is achieved through a quorum-sensing (QS) system consisting of the acyl-homoserine lactone (AHL) synthase, EsaI, and the transcription regulator EsaR. At low cell densities, EsaR represses transcription of itself and of rcsA, an activator of the stewartan biosynthesis operon; it also activates esaS, which encodes a small RNA (sRNA). Repression or activation ceases at high cell densities when EsaI synthesizes sufficient levels of the AHL ligand N-3-oxo-hexanoyl-L-homoserine lactone to bind and inactivate EsaR. This study aims to identify other genes activated or repressed by EsaR during the QS response. Proteomic analysis identified a QS regulon of more than 30 proteins. Electrophoretic mobility shift assays of promoters of genes encoding differentially expressed proteins distinguished direct targets of EsaR from indirect targets. Additional quantitative reverse transcription-PCR (qRT-PCR) and DNA footprinting analysis established that EsaR directly regulates the promoters of dkgA, glpF, and lrhA. The proteins encoded by dkgA, glpF, and lrhA are a 2,5-diketogluconate reductase, glycerol facilitator, and transcriptional regulator of chemotaxis and motility, respectively, indicating a more global QS response in P. stewartii than previously recognized.

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“…Wzi homologs are absent in organisms that use a Wzy-dependent pathway to synthesize secreted EPSs, e.g., colanic acid EPSs in E. coli (Rahn et al., 1999; Reid and Whitfield, 2005), the amylovoran and stewartan biosynthetic pathways in Erwinia spp. (Bugert and Geider, 1995; Carlier et al., 2009). …”

Section: Introductionmentioning

confidence: 99%

Wzi Is an Outer Membrane Lectin that Underpins Group 1 Capsule Assembly in Escherichia coli

et al. 2013

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SummaryMany pathogenic bacteria encase themselves in a polysaccharide capsule that provides a barrier to the physical and immunological challenges of the host. The mechanism by which the capsule assembles around the bacterial cell is unknown. Wzi, an integral outer-membrane protein from Escherichia coli, has been implicated in the formation of group 1 capsules. The 2.6 Å resolution structure of Wzi reveals an 18-stranded β-barrel fold with a novel arrangement of long extracellular loops that blocks the extracellular entrance and a helical bundle that plugs the periplasmic end. Mutagenesis shows that specific extracellular loops are required for in vivo capsule assembly. The data show that Wzi binds the K30 carbohydrate polymer and, crucially, that mutants functionally deficient in vivo show no binding to K30 polymer in vitro. We conclude that Wzi is a novel outer-membrane lectin that assists in the formation of the bacterial capsule via direct interaction with capsular polysaccharides.

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Identification and characterization of three novel EsaI/EsaR quorum‐sensing controlled stewartan exopolysaccharide biosynthetic genes in Pantoea stewartii ssp. stewartii

Cited by 31 publications

References 48 publications

The AHL- and BDSF-Dependent Quorum Sensing Systems Control Specific and Overlapping Sets of Genes in Burkholderia cenocepacia H111

The AHL- and BDSF-Dependent Quorum Sensing Systems Control Specific and Overlapping Sets of Genes in Burkholderia cenocepacia H111

Proteomic Analysis of the Quorum-Sensing Regulon in Pantoea stewartii and Identification of Direct Targets of EsaR

Wzi Is an Outer Membrane Lectin that Underpins Group 1 Capsule Assembly in Escherichia coli

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