FlhG

Manipulation of biofilm formation in Shewanella is beneficial for application to industrial and environmental biotechnology. BpfA is an adhesin largely responsible for biofilm formation in many Shewanella species. However, the mechanism underlying BpfA production and the resulting biofilm remains vaguely understood. We previously described the finding that BpfA expression is enhanced by DosD, an oxygen-stimulated diguanylate cyclase, under aerobic growth. In the present work, we identify FlrA as a critical transcription regulator of the bpfA operon in Shewanella putrefaciens CN32 by transposon mutagenesis...

The marine bacterium Vibrio alginolyticus has a single polar flagellum, the number of which is regulated positively by FlhF and negatively by FlhG. FlhF is intrinsically localized at the cell pole, whereas FlhG is localized there through putative interactions with the polar landmark protein HubP. Here we focused on the role of HubP in the regulation of flagellar number in V. alginolyticus Deletion of hubP increased the flagellar number and completely disrupted the polar localization of FlhG. It was thought that the flagellar number is determined primarily by the absolute amount of FlhF localized at the cell pole...

Yesso scallop-pathogenic Vibrio splendidus strain JZ6 was found to have the highest virulence at 10°C, while its pathogenicity was significantly reduced with increased temperature and completely incapacitated at 28°C. In the present study, comparative transcriptome analyses of JZ6 and another nonpathogenic V. splendidus strain, TZ19, were conducted at two crucial culture temperatures (10°C and 28°C) in order to determine the possible mechanism of temperature regulation of virulence. Comparisons among four libraries, constructed from JZ6 and TZ19 cultured at 10°C and 28°C (designated JZ6_10, JZ6_28, TZ19_10, and TZ19_28), revealed that 241 genes were possibly related to the increased virulence of JZ6 at 10°C...

Bacteria differ in number and location of their flagella that appear in regular patterns at the cell surface (flagellation pattern). Despite the plethora of bacterial species, only a handful of these patterns exist. The correct flagellation pattern is a prerequisite for motility, but also relates to biofilm formation and the pathogenicity of disease-causing flagellated bacteria. However, the mechanisms that maintain location and number of flagella are far from being understood. Here, we review our knowledge on mechanisms that enable bacteria to maintain their appropriate flagellation pattern...

Rod-shaped bacterial cells are polarized, with many organelles confined to a polar cellular site. In polar flagellates, FlhF and FlhG, a multiple-domain (B-N-G) GTPase and a MinD-like ATPase respectively, function as a cognate pair to regulate flagellar localization and number as revealed in Vibrio and Pseudomonas species. In this study, we show that FlhFG of Shewanella oneidensis (SoFlhFG), a monotrichous γ-proteobacterium renowned for respiratory diversity, also play an important role in the flagellar polar placement and number control...

FlhG, a MinD homolog and an ATPase, is known to mediate the formation of the single polar flagellum of Vibrio alginolyticus together with FlhF. FlhG and FlhF work antagonistically, with FlhF promoting flagellar assembly and FlhG inhibiting it. Here, we demonstrate that purified FlhG exhibits a low basal ATPase activity. As with MinD, the basal ATPase activity of FlhG can be activated and the D171A residue substitution enhances its ATPase activity sevenfold. FlhG-D171A localizes strongly at the cell pole and severely inhibits motility and flagellation, whereas the FlhG K31A and K36Q mutants, which are defective in ATP binding, do not localize to the poles, cannot complement a flhG mutant and lead to hyperflagellation...

The number and location of flagella, bacterial organelles of locomotion, are species specific and appear in regular patterns that represent one of the earliest taxonomic criteria in microbiology. However, the mechanisms that reproducibly establish these patterns during each round of cell division are poorly understood. FlhG (previously YlxH) is a major determinant for a variety of flagellation patterns. Here, we show that FlhG is a structural homolog of the ATPase MinD, which serves in cell-division site determination...

The bacterial flagellum is a motility structure and represents one of the most sophisticated nanomachines in the biosphere. Here, we review the current knowledge on the flagellum, its architecture with respect to differences between Gram-negative and Gram-positive bacteria and other species-specific variations (e.g. the flagellar filament protein, Flagellin). We further focus on the mechanism by which the two nucleotide-binding proteins FlhF and FlhG ensure the correct reproduction of flagella place and number (the flagellation pattern)...

Control of surface organelle number and placement is a crucial aspect of the cell biology of many Gram-positive and Gram-negative bacteria, yet mechanistic insights into how bacteria spatially and numerically organize organelles are lacking. Many surface structures and internal complexes are spatially restricted in the bacterial cell (e.g. type IV pili, holdfasts, chemoreceptors), but perhaps none show so many distinct patterns in terms of number and localization as the flagellum. In this review, we discuss two proteins, FlhF and FlhG (also annotated FleN/YlxH), which control aspects of flagellar assembly, placement and number in polar flagellates, and may influence flagellation in some bacteria that produce peritrichous flagella...

The marine bacterium Vibrio alginolyticus has a single polar flagellum. Formation of that flagellum is regulated positively and negatively by FlhF and by FlhG, respectively. The ΔflhF mutant makes no flagellum, whereas the ΔflhFG double-deletion mutant usually lacks a flagellum. However, the ΔflhFG mutant occasionally reverts to become motile by forming peritrichous flagella. We have isolated a suppressor pseudorevertant from the ΔflhFG strain (ΔflhFG-sup). The suppressor strain forms peritrichous flagella in the majority of cells...

Bacterial flagella are highly conserved molecular machines that have been extensively studied for assembly, function and gene regulation. Less studied is how and why bacteria differ based on the number and arrangement of the flagella they synthesize. Here we explore the cell biology of peritrichous flagella in the model bacterium Bacillus subtilis by fluorescently labelling flagellar basal bodies, hooks and filaments. We find that the average B. subtilis cell assembles approximately 26 flagellar basal bodies and we show that basal body number is controlled by SwrA...

Spatial and numerical regulation of flagellar biosynthesis results in different flagellation patterns specific for each bacterial species. Campylobacter jejuni produces amphitrichous (bipolar) flagella to result in a single flagellum at both poles. These flagella confer swimming motility and a distinctive darting motility necessary for infection of humans to cause diarrheal disease and animals to promote commensalism. In addition to flagellation, symmetrical cell division is spatially regulated so that the divisome forms near the cellular midpoint...

In bacteria, large G domain GTPases have well-established functions in translation, protein translocation, tRNA modification and ribosome assembly. In addition, bacteria also contain small Ras-like GTPases consisting of stand-alone G domains. Recent data have revealed that small Ras-like GTPases as well as large G domain GTPases in bacteria function in the regulation of cell polarity, signal transduction and possibly also in cell division. The small Ras-like GTPase MglA together with its cognate GAP MglB regulates cell polarity in Myxococcus xanthus, and the small Ras-like GTPase CvnD9 in Streptomyces coelicolor is involved in signal transduction...

Aeromonas hydrophila polar-flagellum class I gene transcription is σ70 dependent, which is consistent with the fact that the A. hydrophila polar flagellum is constitutively expressed. In contrast to other bacteria with dual flagellar systems such as Vibrio parahaemolyticus, the A. hydrophila LafK protein does not compensate for the lack of the polar-flagellum regulator FlrA (V. parahaemolyticus FlaK homologue). This is consistent with the fact that the A. hydrophila FlrA mutation abolishes polar-flagellum formation in liquid and on solid surfaces but does not affect inducible lateral-flagellum formation...

Precise regulation of the number and positioning of flagella are critical in order for the mono-polar-flagellated bacterium Vibrio alginolyticus to swim efficiently. It has been shown that, in V. alginolyticus cells, the putative GTPase FlhF determines the polar location and production of flagella, while the putative ATPase FlhG interacts with FlhF, preventing it from localizing at the pole, and thus negatively regulating the flagellar number. In fact, no ΔflhF cells have flagella, while a very small fraction of ΔflhFG cells possess peritrichous flagella...

Precise regulation of the number and placement of flagella is critical for the mono-flagellated bacterium Vibrio alginolyticus to swim efficiently. We previously proposed a model in which the putative GTPase FlhF determines the polar location and generation of the flagellum, the putative ATPase FlhG interacts with FlhF to prevent FlhF from localizing to the pole, and thus FlhG negatively regulates the flagellar number in V. alginolyticus cells. To investigate the role of the GTP-binding motif of FlhF, we generated a series of alanine-replacement mutations at the positions that are highly conserved among homologous proteins...

Precise regulation of the number and placement of flagella is critical for the mono-polar-flagellated bacterium Vibrio alginolyticus to swim efficiently. We have shown previously that the number of polar flagella is positively regulated by FlhF and negatively regulated by FlhG. We now show that DeltaflhF cells are non-flagellated as are most DeltaflhFG cells; however, some of the DeltaflhFG cells have several flagella at lateral positions. We found that FlhF-GFP was localized at the flagellated pole, and its polar localization was seen more intensely in DeltaflhFG cells...

The number and location of bacterial flagella vary with the species. The Vibrio alginolyticus cell has a single polar flagellum, which is driven by sodium ions. We selected mutants on the basis of reduced swarming ability on soft agar plates. Among them, we found two mutants with multiple polar flagella, and named them KK148 and NMB155. In Pseudomonas species, it is known that FlhF and FleN, which are FtsY and MinD homologs, respectively, are involved in regulation of flagellar placement and number, respectively...

Vibrio cholerae, the causative agent of the human diarrheal disease cholera, is a motile bacterium with a single polar flagellum, and motility has been inferred to be an important aspect of virulence. The V. cholerae flagellar hierarchy is organized into four classes of genes. The expression of each class of genes within a flagellar hierarchy is generally tightly regulated in other bacteria by both positive and negative regulatory elements. To further elucidate flagellar biogenesis in V. cholerae, we characterized the roles of the three putative regulatory genes, flhF, flhG, and VC2061...