RscS Functions Upstream of SypG To Control the
            <i>syp</i>
            Locus and Biofilm Formation in
            <i>Vibrio fischeri</i>

Hussa, Elizabeth A.; Darnell, Cynthia L.; Visick, Karen L.

doi:10.1128/jb.00130-08

Cited by 65 publications

(115 citation statements)

References 46 publications

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“…(i) SypG is a response regulator that is required for phenotypes induced by pRscS ϩ , including syp transcription and biofilm formation; it is predicted to be the direct transcriptional activator of the syp locus (16, 50). (ii) SypE is a second response regulator, which appears to play both positive and negative roles in biofilm formation (16,27). (iii) SypF, a predicted sensor kinase, also influences biofilm formation (5).…”

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Roles of the Structural Symbiosis Polysaccharide (syp) Genes in Host Colonization, Biofilm Formation, and Polysaccharide Biosynthesis in Vibrio fischeri

et al. 2012

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The symbiosis polysaccharide locus, syp, is required for Vibrio fischeri to form a symbiotic association with the squid Euprymna scolopes. It is also required for biofilm formation induced by the unlinked regulator RscS. The syp locus includes 18 genes that can be classified into four groups based on putative function: 4 genes encode putative regulators, 6 encode glycosyltransferases, 2 encode export proteins, and the remaining 6 encode proteins with other functions, including polysaccharide modification. To understand the roles of each of the 14 structural syp genes in colonization and biofilm formation, we generated nonpolar inframe deletions of each gene. All of the deletion mutants exhibited defects in their ability to colonize juvenile squid, although the impact of the loss of SypB or SypI was modest. Consistent with their requirement for colonization, most of the structural genes were also required for RscS-induced biofilm formation. In particular, the production of wrinkled colonies, pellicles, and the matrix on the colony surface was eliminated or severely decreased in all mutants except for the sypB and sypI mutants; in contrast, only a subset of genes appeared to play a role in attachment to glass. Finally, immunoblotting data suggested that the structural Syp proteins are involved in polysaccharide production and/or export. These results provide important insights into the requirements for the syp genes under different environmental conditions and thus lay the groundwork for a more complete understanding of the matrix produced by V. fischeri to enhance cell-cell interactions and promote symbiotic colonization.T he initial interactions between microbes and their hosts are critical to the establishment of both symbiotic and pathogenic associations. The adherence of the microbe to its host and bacterial cell-cell aggregation are two processes that can mediate these initial interactions. The roles of polysaccharides in promoting adherence and cell-cell interactions in pathogenic and symbiotic colonization are well recognized (29, 37). Bacterial lipopolysaccharides (LPS), for example, can mediate the adherence of bacterial cells to various cellular components, such as mannose receptors and mucus (17,34). Capsular polysaccharides (CPS) and/or exopolysaccharides (EPS), present on the bacterial surface and secreted, respectively, can promote adherence to host or abiotic surfaces by facilitating the formation of biofilms and thus increasing colonization efficiency (4).To understand bacterium-host and bacterium-bacterium interactions during the colonization of a host, we have used the symbiosis between the bacterium Vibrio fischeri and its host, the squid Euprymna scolopes, as a model system (30). We previously obtained evidence that one or more polysaccharides are important for the ability of V. fischeri to colonize its host (5, 36, 49, 50). In particular, V. fischeri depends upon the 18-gene symbiosis polysaccharide (syp) locus for efficient colonization: the insertional mutation of several syp genes reduced ...

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Roles of the Structural Symbiosis Polysaccharide (syp) Genes in Host Colonization, Biofilm Formation, and Polysaccharide Biosynthesis in Vibrio fischeri

et al. 2012

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“…This phenotype, like wrinkled colonies, is induced by rscS overexpression and depends upon the syp locus (17,23). Although we previously observed a strong correlation between the formation of wrinkled colonies and the formation of pellicles (17,20,23,25,26), this was not the case for the bmp mutant: despite being unable to form a wrinkled colony, the bmp mutant was competent to form a pellicle (Fig. 4).…”

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“…These data suggested that while the bmp genes are not required for pellicle formation per se, they may be involved in the maturation of the V. fischeri biofilm by building and/or maintaining the three-dimensional (3D) architecture of the biofilm. Additionally, because the syp locus is necessary for pellicle formation (20,23,25), these data suggested that the bmp mutant may still produce the Syp polysaccharide, a possibility that we address below.…”

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confidence: 99%

“…The signal recognized by RscS is unknown, but overexpression of the rscS gene is sufficient to induce syp transcription and promote biofilm phenotypes, including the formation of wrinkled colonies (normally smooth) and pellicles (not normally formed) (17). Overexpression of sypG induces syp transcription to an even greater extent but fails to promote biofilm formation due to the presence of an additional RscS-responsive control mechanism that functions below syp transcription (18,23,25,26). Although much is known about the regulatory control over Syp polysaccharide production, important aspects of V. fischeri biofilm formation, including the identities of other matrix components, such as matrix proteins, remain unknown.…”

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“…Biofilm formation by V. fischeri requires the symbiosis polysaccharide (syp) locus, an 18-gene locus that encodes proteins for the production and transport of a polysaccharide critical for biofilm formation and host colonization (17,19,20). The syp locus is regulated by a two-component signal transduction system that includes the sensor kinase RscS (17, 21) and the response regulator SypG (19,22,23). Upon sensing an unknown signal, RscS is predicted to initiate a phosphorelay that leads to the phosphorylation and activation of SypG (Fig.…”

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Identification of a Novel Matrix Protein That Promotes Biofilm Maturation in Vibrio fischeri

Ray¹,

Driks²,

Visick³

2014

J. Bacteriol.

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Bacteria form communities, termed biofilms, in which cells adhere to each other within a matrix, typically comprised of polysaccharides, proteins, and extracellular DNA. Biofilm formation by the marine bacterium Vibrio fischeri requires the Syp polysaccharide, but the involvement of matrix proteins is as yet unknown. Here we identified three genes, termed bmpA, -B, and -C (biofilm maturation protein), with overlapping functions in biofilm maturation. A triple bmpABC mutant, but not single or double mutants, was defective in producing wrinkled colonies, a form of biofilm. Surprisingly, the triple mutant was competent to form pellicles, another biofilm phenotype, but they generally lacked a three-dimensional architecture. Transmission electron microscopy revealed that the extracellular matrix of the bmp mutant contained electron-dense, thread-like structures that were also present in the wild type but lacking in syp mutant strains. We hypothesized that the bmp mutant produces the Syp polysaccharide but fails to produce/export a distinct matrix component. Indeed, a mixture of the bmp and syp mutants produced a wrinkled colony. Finally, BmpA could be detected in cell-free supernatants from disrupted pellicles. Thus, this work identifies a new matrix protein necessary for biofilm maturation by V. fischeri and, based on the conservation of bmp, potentially other microbes. Bacteria can be found as planktonic cells or within sessile communities called biofilms, which are composed of bacterial cells encased in an extracellular matrix (1-3). The matrix is generally self-produced and comprised of polysaccharides, proteins, extracellular DNA, and other bacterial products, such as outer membrane vesicles (OMVs). These matrix components promote adherence of the bacteria to each other and to a variety of surfaces, including host tissues and medical devices, such as catheters (reviewed in reference 4). Furthermore, due at least in part to the protective nature of the matrix, resident cells exhibit increased resistance to predation (5), desiccation (6), host defenses (4), and antibiotics (7). While much is known about the process of biofilm formation and its regulation from the study of a variety of bacteria, we still know little about the constituents of the matrix, in particular the matrix proteins, and their contributions to biofilm formation.Matrix proteins can be anchored to or associated with the cell surface or released into the extracellular space, where they appear to promote cell-matrix, cell-cell, matrix-matrix, and cell-surface interactions. For example, in Pseudomonas aeruginosa, the matrix protein CdrA is both cell associated and secreted and likely promotes cell-matrix and matrix-matrix interactions by binding to the Psl polysaccharide (8), which itself is cell associated and secreted (9). Additionally, the lectins LecA, specific for D-galactose (10), and LecB, specific for L-fucose (11), are thought to promote cell-cell interactions (12) during P. aeruginosa biofilm formation.Perhaps the most is known about the r...

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The putative oligosaccharide translocase SypK connects biofilm formation with quorum signaling in V ibrio fischeri

et al. 2014

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Quorum signaling (QS) describes how bacteria can use small signaling molecules (autoinducers) to coordinate group-level behaviors. In Vibrio fischeri, QS is achieved through a complex regulatory network that ultimately controls bioluminescence, motility, and host colonization. We conducted a genetic screen focused on qrr1, which encodes a small regulatory RNA that is necessary for the core quorum-signaling cascade to transduce autoinducer information into cellular responses. We isolated unique mutants with a transposon inserted into one of two genes within the syp locus, which is involved in biofilm formation. We found that overexpression of sypK, which encodes a putative oligosaccharide translocase, is sufficient to activate qrr1, and, in addition, this effect appears to depend on the kinase activity of the sensor LuxQ. Consistent with the established model for QS in V. fischeri, enhanced expression of qrr1 by the overexpression of sypK resulted in reduced bioluminescence and increased motility. Finally, we found that induction of the syp locus by overexpression of sypG was sufficient to activate qrr1 levels. Together, our results show how conditions that promote biofilm formation impact the quorum-signaling network in V. fischeri, and further highlight the integrated nature of the regulatory circuits involved in complex bacterial behaviors.

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RscS Functions Upstream of SypG To Control the syp Locus and Biofilm Formation in Vibrio fischeri

Cited by 65 publications

References 46 publications

Roles of the Structural Symbiosis Polysaccharide (syp) Genes in Host Colonization, Biofilm Formation, and Polysaccharide Biosynthesis in Vibrio fischeri

Roles of the Structural Symbiosis Polysaccharide (syp) Genes in Host Colonization, Biofilm Formation, and Polysaccharide Biosynthesis in Vibrio fischeri

Identification of a Novel Matrix Protein That Promotes Biofilm Maturation in Vibrio fischeri

The putative oligosaccharide translocase SypK connects biofilm formation with quorum signaling in V ibrio fischeri

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