Genetic Determinants of<i>Silicibacter</i>sp. TM1040 Motility

Belas, Robert; Horikawa, Eiko; Aizawa, Shin‐Ichi; Suvanasuthi, Rooge

doi:10.1128/jb.00429-09

Cited by 44 publications

(63 citation statements)

References 38 publications

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“…In Rhodobacter capsulatus (Mercer et al, 2010) and Silicibacter sp. TM1040 (Belas et al, 2009) the growth rate of the culture was not affected by knockout of ctrA. However, in the latter strain the knockout leads to elongated cells.…”

Section: Discussionmentioning

confidence: 92%

“…Thus, the metabolic costs for flagellar synthesis are only worth spending in a diffusion-limited patchy microenvironment where motility might provide the chance to reach more optimal conditions or nutrients, a classical condition for QS. In Roseobacters, flagella have been shown to enable chemotaxis towards dimethylsulfono-propionate (DMSP), a storage compound and osmoprotectant synthesized by marine algae (Belas et al, 2009). Flagella mutants have been shown to be impaired in their ability to form biofilms on abiotic surfaces and were not able to attach to diatoms (Sonnenschein et al, 2012) or dinoflagellates (Miller and Belas, 2006).…”

Section: Discussionmentioning

confidence: 99%

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You are what you talk: quorum sensing induces individual morphologies and cell division modes in Dinoroseobacter shibae

Patzelt

Wang

Buchholz³

et al. 2013

The ISME Journal

117

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Dinoroseobacter shibae, a member of the Roseobacter clade abundant in marine environments, is characterized by a pronounced pleomorphism. Cell shapes range from variable-sized ovoid rods to long filaments with a high copy number of chromosomes. Time-lapse microscopy shows cells dividing either by binary fission or by budding from the cell poles. Here we demonstrate that this morphological heterogeneity is induced by quorum sensing (QS). D. shibae utilizes three acylated homoserine lactone (AHL) synthases (luxI 1-3 ) to produce AHLs with unsaturated C18 side chains. A DluxI 1 -knockout strain completely lacking AHL biosynthesis was uniform in morphology and divided by binary fission only. Transcriptome analysis revealed that expression of genes responsible for control of cell division was reduced in this strain, providing the link between QS and the observed phenotype. In addition, flagellar biosynthesis and type IV secretion system (T4SS) were downregulated. The wild-type phenotype and gene expression could be restored through addition of synthetic C18-AHLs. Their effectiveness was dependent on the number of double bonds in the acyl side chain and the regulated trait. The wild-type expression level of T4SS genes was fully restored even by an AHL with a saturated C18 side chain that has not been detected in D. shibae. QS induces phenotypic individualization of D. shibae cells rather than coordinating the population. This strategy might be beneficial in unpredictably changing environments, for example, during algal blooms when resource competition and grazing exert fluctuating selective pressures. A specific response towards non-native AHLs might provide D. shibae with the capacity for complex interspecies communication.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

You are what you talk: quorum sensing induces individual morphologies and cell division modes in Dinoroseobacter shibae

Patzelt

Wang

Buchholz³

et al. 2013

The ISME Journal

117

View full text Add to dashboard Cite

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“…In addition to its chromosome harboring Ͼ40 open reading frames (ORFs) required for motility and chemotaxis (15,16), the genome of TM1040 consists of three large plasmids: pSTM1 (823 kb), pSTM2 (131 kb), and pSTM3 (135 kb) (16,17). pSTM3 escaped initial sequencing attempts and is not part of the published genome, but subsequent analyses indicate that it harbors at least six genes required for biosynthesis of the antibiotic and quorum signaling molecule tropodithietic acid (TDA; see Fig.…”

mentioning

confidence: 99%

A Novel Inducer of Roseobacter Motility Is Also a Disruptor of Algal Symbiosis

Sule

Belas

2012

Journal of Bacteriology

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Silicibacter sp. strain TM1040, a member of the Roseobacter clade, forms a symbiosis with unicellular phytoplankton, which is inextricably linked to the biphasic "swim or stick" lifestyle of the bacteria. Mutations in flaC bias the population toward the motile phase. Renewed examination of the FlaC ؊ strain (HG1016) uncovered that it is composed of two different cells: a pigmented type, PS01, and a nonpigmented cell, PS02, each of which has an identical mutation in flaC. While monocultures of PS01 and PS02 had few motile cells (0.6 and 6%, respectively), coculturing the two strains resulted in a 10-fold increase in the number of motile cells. Cell-free supernatants from coculture or wild-type cells were fully capable of restoring motility to PS01 and PS02, which was due to increased fliC3 (flagellin) transcription, FliC3 protein levels per cell, and flagella synthesis. The motility-inducing compound has an estimated mass of 226 Da, as determined by mass spectrometry, and is referred to as Roseobacter Motility Inducer (RMI). Mutations affecting genes involved in phenyl acetic acid synthesis significantly reduced RMI, while defects in tropodithietic acid (TDA) synthesis had marginal or no effect on RMI. RMI biosynthesis is induced by p-coumaric acid, a product of algal lignin degradation. When added to algal cultures, RMI caused loss of motility, cell enlargement, and vacuolization in the algal cells. RMI is a new member of the roseobacticide family of troponoid compounds whose activities affect roseobacters, by shifting their population toward motility, as well as their phytoplankton hosts, through an algicidal effect.

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“…FlbT homologues are well-distributed among the alphaproteobacteria, including the free-living bacterium C. crescentus, the plant symbiont bacterium S. meliloti and B. melitensis (Belas et al, 2009;Hoang et al, 2008;Kanbe et al, 2007;Llewellyn et al, 2005; Supplementary Fig. S1).…”

Section: The Function Of Flbt Is Conserved In Members Of the Order Rhmentioning

confidence: 99%

“…2e). Altogether, these data clearly demonstrate that FlbT is required for fliC expression and FliC synthesis.Like FlbT, FlaF is also conserved among the alphaproteobacteria and is generally located upstream of flbT (Bahlawane et al, 2008;Belas et al, 2009;Kanbe et al, 2007;Llewellyn et al, 2005) ( Supplementary Fig. S3, available with the online version of this paper).…”

mentioning

confidence: 99%

Role of FlbT in flagellin production in Brucella melitensis

2011

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It was recently demonstrated that the pathogen Brucella melitensis produces a polar sheathed flagellum under the control of the master regulator FtcR. However, the regulatory mechanism controlling the flagellar assembly remains unknown. In this work, we investigate the flagellar hierarchy of B. melitensis as well as the flagellin FliC regulation. We show that a mutation in fliF or flgE (coding for the basal body structure and the hook, respectively) does not affect FliC synthesis, suggesting that production of FliC does not depend on the flagellar assembly. We demonstrate that FlbT is a FliC activator since inactivation of flbT causes a decrease in fliC expression by using a fliC-lacZ translational reporter construct. Moreover, the quantitative realtime PCR and Western blot analysis show a marked decrease in fliC mRNA and FliC protein level, respectively. Conversely, the B. melitensis wild-type strain overexpressing flaF fails to produce FliC, suggesting an opposite function. Interestingly, the expression of the flbT gene in an ftcR or an flbT mutant restores FliC production, demonstrating that FlbT plays a regulatory checkpoint role in FliC synthesis. This mechanism could be conserved in the Rhizobiales since complementation of an flbT or an ftcR mutant with flbT from Sinorhizobium meliloti restores FliC synthesis. INTRODUCTIONThe intracellular pathogen Brucella melitensis is the causative agent of brucellosis in mammals, also known as Malta fever in humans. This intracellular pathogen belongs to the a-2 subgroup of proteobacteria, including the genera Agrobacterium, Rhizobium and Rickettsia, which also live in close association with a eukaryotic host (Batut et al., 2004;Ugalde, 1999). For a long time, brucella was considered to be non-flagellated, but recent studies have demonstrated that B. melitensis produces a polar sheathed flagellum during the beginning of the exponential growth phase in rich medium and that the flagellar genes are required for the establishment of in vivo infection in mice and goats (Ferooz & Letesson, 2010;Fretin et al., 2005;Letesson et al., 2002;Zygmunt et al., 2006).The structure of the bacterial flagellum is classically divided into three main components: the MS-ring in the basal body, the hook and the filament encoded by the fliF, flgE and fliC genes, respectively. The molecular processes involved in assembly of the bacterial flagellum have been extensively studied in the enterobacteria Escherichia coli and Salmonella enterica serovar Typhimurium (Macnab, 1996). In these organisms, the flagellar genes are divided into three different classes hierarchically controlled by a finely tuned mechanism (Chevance & Hughes, 2008; Frye et al., 2006;Kalir et al., 2001). At the first step of flagellar assembly, the class I transcriptional regulator FlhDC activates the transcription of the class II genes which include the genes encoding the structural components of the hook-basal body (HBB) structure, the sigma factor 28 (s 28 also named FliA), which activates the class III genes, and its anti-...

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Genetic Determinants ofSilicibactersp. TM1040 Motility

Cited by 44 publications

References 38 publications

You are what you talk: quorum sensing induces individual morphologies and cell division modes in Dinoroseobacter shibae

You are what you talk: quorum sensing induces individual morphologies and cell division modes in Dinoroseobacter shibae

A Novel Inducer of Roseobacter Motility Is Also a Disruptor of Algal Symbiosis

Role of FlbT in flagellin production in Brucella melitensis

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