FlhF, a signal recognition particle-like GTPase, is involved in the regulation of flagellar arrangement, motility behaviour and protein secretion in Bacillus cereus

Salvetti, Sara; Ghelardi, Emilia; Celandroni, Francesco; Ceragioli, Mara; Giannessi, Franco; Senesi, Sonia

doi:10.1099/mic.0.2006/005553-0

Cited by 52 publications

(77 citation statements)

References 41 publications

(79 reference statements)

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“…With the exception of Bacillus spp., the commonly studied peritrichously flagellated bacteria do not carry flhF. In Bacillus cereus, deletion of flhF leads to a reduction in flagellar number rather than to a change in flagellar position (9).…”

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confidence: 99%

The GTPase Activity of FlhF Is Dispensable for Flagellar Localization, but Not Motility, in Pseudomonas aeruginosa

Schniederberend

Abdurachim

Murray

et al. 2012

Journal of Bacteriology

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The opportunistic human pathogen Pseudomonas aeruginosa uses two surface organelles, flagella and pili, for motility and adhesion in biotic and abiotic environments. Polar flagellar placement and number are influenced by FlhF, which is a signal recognition particle (SRP)-type GTPase. The FlhF proteins of Bacillus subtilis and Campylobacter jejuni were recently shown to have GTPase activity. However, the phenotypes associated with flhF deletion and/or mutation differ between these organisms and P. aeruginosa, making it difficult to generalize a role for FlhF in pseudomonads. In this study, we confirmed that FlhF of P. aeruginosa binds and hydrolyzes GTP. We mutated FlhF residues that we predicted would alter nucleotide binding and hydrolysis and determined the effects of these mutations on FlhF enzymatic activity, protein dimerization, and bacterial motility. Both hydrolytically active and inactive FlhF point mutants restored polar flagellar assembly, as seen for wild-type FlhF. However, differential effects on flagellar function were observed in single-cell assays of swimming motility and flagellar rotation. These findings indicate that FlhF function is influenced by its nucleotide binding and hydrolytic activities and demonstrate that FlhF affects P. aeruginosa flagellar function as well as assembly.

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confidence: 99%

The GTPase Activity of FlhF Is Dispensable for Flagellar Localization, but Not Motility, in Pseudomonas aeruginosa

Schniederberend

Abdurachim

Murray

et al. 2012

Journal of Bacteriology

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“…The FlhF GTPase of vibrios, pseudomonads, and Campylobacter jejuni may function akin to the TipF and c-di-GMP-dependent flagellar polarization pathway (Pandza et al 2000;Salvetti et al 2007;Balaban et al 2009;Kusumoto et al 2009). FlhF is polarized and recruits the MS ring protein FliF to the polar site of flagellation in Vibrio.…”

Section: Discussionmentioning

confidence: 99%

De- and repolarization mechanism of flagellar morphogenesis during a bacterial cell cycle

et al. 2013

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Eukaryotic morphogenesis is seeded with the establishment and subsequent amplification of polarity cues at key times during the cell cycle, often using (cyclic) nucleotide signals. We discovered that flagellum de-and repolarization in the model prokaryote Caulobacter crescentus is precisely orchestrated through at least three spatiotemporal mechanisms integrated at TipF. We show that TipF is a cell cycle-regulated receptor for the second messenger-bis-(39-59)-cyclic dimeric guanosine monophosphate (c-di-GMP)-that perceives and transduces this signal through the degenerate c-di-GMP phosphodiesterase (EAL) domain to nucleate polar flagellum biogenesis. Once c-di-GMP levels rise at the G1 / S transition, TipF is activated, stabilized, and polarized, enabling the recruitment of downstream effectors, including flagellar switch proteins and the PflI positioning factor, at a preselected pole harboring the TipN landmark. These c-di-GMP-dependent events are coordinated with the onset of tipF transcription in early S phase and together enable the correct establishment and robust amplification of TipF-dependent polarization early in the cell cycle. Importantly, these mechanisms also govern the timely removal of TipF at cell division coincident with the drop in c-di-GMP levels, thereby resetting the flagellar polarization state in the next cell cycle after a preprogrammed period during which motility must be suspended.

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“…The genotypes and sources of the bacterial strains and plasmids used in this study are listed in Table 1. B. cereus and E. coli were grown in Luria-Bertani (LB) broth or LB agar at 37°C, with vigorous shaking (41). The bacterial growth rate was monitored by measuring the absorbance of the medium with a GeneQuant Pro spectrophotometer (GE Healthcare) at 600 nm.…”

Section: Methodsmentioning

confidence: 99%

orf4 of the Bacillus cereus sigB Gene Cluster Encodes a General Stress-Inducible Dps-Like Bacterioferritin

et al. 2009

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The function of orf4 in the sigB cluster in Bacillus cereus ATCC 14579 remains to be explored. Amino-acid sequence analysis has revealed that Orf4 is homologous with bacterioferritins and Dps. In this study, we generated an orf4-null mutant and produced recombinant protein rOrf4 to establish the role of orf4. In vitro, the purified rOrf4 was found to exist in two distinct forms, a dimeric form and a polymer form, through size exclusion analysis. The latter form exhibited a unique filament structure, in contrast to the typical spherical tetracosamer structure of bacterioferritins; the former can be induced to form rOrf4 polymers immediately after the addition of FeCl 2 . Catalysis of the oxidation of ferrous irons by ferroxidase activity was detected with rOrf4, and the mineralized irons were subsequently sequestered only in the rOrf4 polymer. Moreover, rOrf4 exerted DNA-protective activity against oxidative damage via DNA binding in a nonspecific manner, as is seen with Dps. In vivo, deletion of orf4 had no effect on activation of the alternative sigma factor B , and therefore, orf4 is not associated with B regulation; however, orf4 can be significantly upregulated upon environmental stress but not H 2 O 2 treatment. B. cereus strains with constitutive Orf4 expression exhibited a viability higher than that of the orf4-null mutant, under specific oxidative stress or heat shock. Taken together, these results suggest that Orf4 functions as a Dps-like bacterioferritin in response to environmental stress and can provide cell protection from oxidative damage through iron sequestration and DNA binding.

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FlhF, a signal recognition particle-like GTPase, is involved in the regulation of flagellar arrangement, motility behaviour and protein secretion in Bacillus cereus

Cited by 52 publications

References 41 publications

The GTPase Activity of FlhF Is Dispensable for Flagellar Localization, but Not Motility, in Pseudomonas aeruginosa

The GTPase Activity of FlhF Is Dispensable for Flagellar Localization, but Not Motility, in Pseudomonas aeruginosa

De- and repolarization mechanism of flagellar morphogenesis during a bacterial cell cycle

orf4 of the Bacillus cereus sigB Gene Cluster Encodes a General Stress-Inducible Dps-Like Bacterioferritin

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