Chapter 8 Deciphering Bacterial Flagellar Gene Regulatory Networks in the Genomic Era

Smith, Todd G.; Hoover, Timothy R.

doi:10.1016/s0065-2164(08)01008-3

Cited by 89 publications

(102 citation statements)

References 205 publications

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“…1B, lane 3), revealing that FliC may repress fliD gene expression. In Gram-negative bacteria, flagellum production and regulation of motility involve more than 40 different genes (1,20,31). More work is clearly needed to further understand the regulation of flagellar expression and function in C. difficile.…”

Section: Discussionmentioning

confidence: 99%

Mutagenic Analysis of the Clostridium difficile Flagellar Proteins, FliC and FliD, and Their Contribution to Virulence in Hamsters

2011

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Although toxins A and B are known to be important contributors to the acute phase of Clostridium difficile infection, the role of colonization and adherence to host tissues in the overall pathogenesis of these organisms remains unclear. Consequently, we used the recently introduced intron-based ClosTron gene interruption system to eliminate the expression of two reported C. difficile colonization factors, the major flagellar structural subunit (FliC) and the flagellar cap protein (FliD), to gain greater insight into how flagella and motility contribute to C. difficile's pathogenic strategy. The results demonstrate that interrupting either the fliC or the fliD gene results in a complete loss of flagella, as well as motility, in C. difficile. However, both the fliC and fliD mutant strains adhered better than the wild-type 630⌬erm strain to human intestine-derived Caco-2 cells, suggesting that flagella and motility do not contribute to, or may even interfere with, C. difficile adherence to epithelial cell surfaces in vitro. Moreover, we found that the mutant strains were more virulent in hamsters, indicating either that flagella are unnecessary for virulence or that repression of motility may be a pathogenic strategy employed by C. difficile in hamsters.

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Section: Discussionmentioning

confidence: 99%

Mutagenic Analysis of the Clostridium difficile Flagellar Proteins, FliC and FliD, and Their Contribution to Virulence in Hamsters

2011

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“…Thus, depending on the species, the regulation of flagellum biosynthesis comprises three or four principal steps, whose stages have been carefully studied in model systems such as Caulobacter crescentus, Ensifer meliloti, Escherichia coli, Pseudomonas spp., Salmonella enterica, and Vibrio spp., among others (12)(13)(14). In general, a master regulator (class I) induces the expression of several flagellar operons (class II) that encode the basal body, the hook and hook-related proteins, and a regulator of the synthesis of the filament monomers or flagellins.…”

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Transcriptional Control of the Lateral-Flagellar Genes of Bradyrhizobium diazoefficiens

et al. 2017

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Bradyrhizobium diazoefficiens, a soybean N 2 -fixing symbiont, possesses a dual flagellar system comprising a constitutive subpolar flagellum and inducible lateral flagella. Here, we analyzed the genomic organization and biosynthetic regulation of the lateral-flagellar genes. We found that these genes are located in a single genomic cluster, organized in two monocistronic transcriptional units and three operons, one possibly containing an internal transcription start site. Among the monocistronic units is blr6846, homologous to the class IB master regulators of flagellum synthesis in Brucella melitensis and Ensifer meliloti and required for the expression of all the lateral-flagellar genes except lafA2, whose locus encodes a single lateral flagellin. We therefore named blr6846 lafR (lateral-flagellar regulator). Despite its similarity to two-component response regulators and its possession of a phosphorylatable Asp residue, lafR behaved as an orphan response regulator by not requiring phosphorylation at this site. Among the genes induced by lafR is flbT L , a class III regulator. We observed different requirements for FlbT L in the synthesis of each flagellin subunit. Although the accumulation of lafA1, but not lafA2, transcripts required FlbT L , the production of both flagellin polypeptides required FlbT L . Moreover, the regulation cascade of this lateral-flagellar regulon appeared to be not as strictly ordered as those found in other bacterial species.IMPORTANCE Bacterial motility seems essential for the free-living style in the environment, and therefore these microorganisms allocate a great deal of their energetic resources to the biosynthesis and functioning of flagella. Despite energetic costs, some bacterial species possess dual flagellar systems, one of which is a primary system normally polar or subpolar, and the other is a secondary, lateral system that is produced only under special circumstances. Bradyrhizobium diazoefficiens, an N 2 -fixing symbiont of soybean plants, possesses dual flagellar systems, including the lateral system that contributes to swimming in wet soil and competition for nodulation and is expressed under high energy availability, as well as under requirement for high torque by the flagella. The structural organization and transcriptional regulation of the 41 genes that comprise this secondary flagellar system seem adapted to adjust bacterial energy expenditures for motility to the soil's environmental dynamics.KEYWORDS Bradyrhizobium, flagella, expression, lafR, flbT, FlbT, LafR F lagellum-driven swimming motility-a characteristic trait of many bacterial species-is essential for the colonization of diverse niches in environments such as seas, freshwaters, sediments, soils, and the organs of plant or animal hosts. This form of bacterial locomotion requires the propulsion provided by flagella, as well as a guidance system mediated by chemotaxis (1).Flagella are complex organelles formed by three main structures: a basal body that anchors the flagellum to the cell envelope...

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“…Where it has been examined, expression of flagellar genes is controlled by a transcriptional hierarchy that coordinates the synthesis of flagellar proteins with assembly of the nascent flagellum (10,11). Transcription of flagellar genes in H. pylori is governed by all three sigma factors found in the bacterium (see Fig.…”

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Requirement of the Flagellar Protein Export Apparatus Component FliO for Optimal Expression of Flagellar Genes in Helicobacter pylori

Tsang

Hoover

2014

J Bacteriol

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Chapter 8 Deciphering Bacterial Flagellar Gene Regulatory Networks in the Genomic Era

Cited by 89 publications

References 205 publications

Mutagenic Analysis of the Clostridium difficile Flagellar Proteins, FliC and FliD, and Their Contribution to Virulence in Hamsters

Mutagenic Analysis of the Clostridium difficile Flagellar Proteins, FliC and FliD, and Their Contribution to Virulence in Hamsters

Transcriptional Control of the Lateral-Flagellar Genes of Bradyrhizobium diazoefficiens

Requirement of the Flagellar Protein Export Apparatus Component FliO for Optimal Expression of Flagellar Genes in Helicobacter pylori

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