Hfq regulates the expression of the thermostable direct hemolysin gene in Vibrio parahaemolyticus

Nakano, Masayuki; Takahashi, Akira; Su, Zehong; Harada, Nagakatsu; Mawatari, Kazuaki; Nakaya, Yutaka

doi:10.1186/1471-2180-8-155

Cited by 34 publications

(25 citation statements)

References 49 publications

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“…The recent reports of the role of Hfq in virulence in the human pathogen Vibrio parahaemolyticus as well as in the fish pathogen Vibrio alginolyticus underscore the likeliness of the importance of sRNAs in virulence in these other species (Nakano et al 2007(Nakano et al , 2008Liu et al 2011).…”

Section: Introductionmentioning

confidence: 98%

Transcriptomic profiling of the oyster pathogen Vibrio splendidus opens a window on the evolutionary dynamics of the small RNA repertoire in the Vibrio genus

Toffano‐Nioche

Nguyen

Kuchly

et al. 2012

RNA

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Work in recent years has led to the recognition of the importance of small regulatory RNAs (sRNAs) in bacterial regulation networks. New high-throughput sequencing technologies are paving the way to the exploration of an expanding sRNA world in nonmodel bacteria. In the Vibrio genus, compared to the enterobacteriaceae, still a limited number of sRNAs have been characterized, mostly in Vibrio cholerae, where they have been shown to be important for virulence, as well as in Vibrio harveyi. In addition, genome-wide approaches in V. cholerae have led to the discovery of hundreds of potential new sRNAs. Vibrio splendidus is an oyster pathogen that has been recently associated with massive mortality episodes in the French oyster growing industry. Here, we report the first RNA-seq study in a Vibrio outside of the V. cholerae species. We have uncovered hundreds of candidate regulatory RNAs, be it cis-regulatory elements, antisense RNAs, and trans-encoded sRNAs. Conservation studies showed the majority of them to be specific to V. splendidus. However, several novel sRNAs, previously unidentified, are also present in V. cholerae. Finally, we identified 28 trans sRNAs that are conserved in all the Vibrio genus species for which a complete genome sequence is available, possibly forming a Vibrio ''sRNA core.''

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Section: Introductionmentioning

confidence: 98%

Transcriptomic profiling of the oyster pathogen Vibrio splendidus opens a window on the evolutionary dynamics of the small RNA repertoire in the Vibrio genus

Toffano‐Nioche

Nguyen

Kuchly

et al. 2012

RNA

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“…Previously, we reported ∆Hfq V. parahaemolyticus had a slower growth rate than the parental strain (Nakano et al, 2008). These indicated that the growth rate and anti-oxidative capability against H 2 O 2 were dependent on different functions.…”

Section: Discussionmentioning

confidence: 88%

“…a reduced growth rate and higher production of thermostable direct hemolysin (TDH) compared with that of the parental strain, which indicated that Hfq had an effect on the growth and was associated with the production of TDH in V. parahaemolyticus (Nakano et al, 2008).…”

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confidence: 99%

Hfq regulates anti-oxidative ability in Vibrio parahaemolyticus

Nakano

Koga

et al. 2010

J. Gen. Appl. Microbiol.

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IntroductionHfq protein plays a fundamental role in bacterial cell physiology. An hfq null mutant of Escherichia coli K-12 displayed pronounced pleiotropic phenotypes, including decreased growth rates and yields, decreased negative supercoiling of plasmids in the stationary phase, increased cell size, osmosensitivity, increased oxidation of carbon sources, and increased sensitivity to ultraviolet light (Gottesman, 2005;Tsui et al., 1994). It was also shown that Hfq is required for uropathogenic Escherichia coli (UPEC) to effectively colonize and persist within the urinary tract. The deletion of hfq led to attenuated UPEC, thereby reducing intracellular growth, diminished tolerance to reactive nitrogen species (RNS), reactive oxygen species (ROS) and the antibacterial cationic peptide polymyxin B, and reduced ability to grow in acidic medium (pH 5.0). Furthermore, the hfq mutant showed reduced motility and chemotaxis and biofi lm formation was signifi cantly impaired (Kulesus et al., 2008). Our previous results also described that hfq mutant V. parahaemolyticus showed J. Gen. Appl. Microbiol., 56, 181 186 (2010) Hfq plays a fundamental role in bacterial cell physiology. It can stimulate or repress the expression of certain target genes, and there is a possibility that Hfq regulates the oxidative stress response. However, how Hfq functions that in Vibrio parahaemolyticus remains speculative. In this paper, we explain the functions Hfq plays in V. parahaemolyticus in the gene expression of superoxide dismutase gene and catalase gene, comparing the hfq deletion mutant strain to the parental strain. The results show that the hfq deletion mutant V. parahaemolyticus has a stronger ability to resist H 2 O 2 . Superoxide dismutase (SOD) and catalase (CAT) activities in the hfq deletion mutant were remarkably higher than in the parental strain. Genetic experiments indicated that the gene expression of sod and kat was up-regulated in the mutant strain. These results indicate that Hfq down-regulates CAT and SOD activity, and Hfq is associated with the oxidative stress response.

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“…Deletions of the vp0920 and vp2911 genes were generated by homologous recombination as reported previously (25). Briefly, ϳ500-bp fragments immediately upstream and downstream of the gene of interest were amplified by PCR using primer pairs (Table 2).…”

Section: Methodsmentioning

confidence: 99%

DNA-Binding Protein HU Coordinates Pathogenicity in Vibrio parahaemolyticus

et al. 2015

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HU is one of the most abundant nucleoid-associated proteins in bacterial cells and regulates the expression of many genes involved in growth, motility, metabolism, and virulence. It is known that Vibrio parahaemolyticus pathogenicity is related to its characteristic rapid growth and that type III secretion system 1 (T3SS1) contributes to its cytotoxicity. However, it is not known if HU plays a role in the pathogenicity of V. parahaemolyticus. In the present study, we investigated the effect of HU proteins HU-2 (HU␣) (V. parahaemolyticus 2911 [vp2911]) and HU␤ (vp0920) on the pathogenicity of V. parahaemolyticus. We found that a deletion of both HU subunits (yielding the ⌬HUs [⌬vp0920 ⌬vp2911] strain), but not single deletions, led to a reduction of the growth rate. In addition, expression levels of T3SS1-related genes, including exsA (positive regulator), exsD (negative regulator), vp1680 (cytotoxic effector), and vp1671 (T3SS1 apparatus), were reduced in the ⌬HUs strain compared to the wild type (WT). As a result, cytotoxicity to HeLa cells was decreased in the ⌬HUs strain. The additional deletion of exsD in the ⌬HUs strain restored T3SS1-related gene expression levels and cytotoxicity but not the growth rate. These results suggest that the HU protein regulates the levels of T3SS1 gene expression and cytotoxicity in a growth rate-independent manner. IMPORTANCENucleoid-binding protein HU regulates cellular behaviors, including nucleoid structuring, general recombination, transposition, growth, replication, motility, metabolism, and virulence. It is thought that both the number of bacteria and the number of virulence factors may affect the pathogenicity of bacteria. In the present study, we investigated which factor(s) has a dominant role during infection in one of the most rapidly growing bacterial species, Vibrio parahaemolyticus. We found that V. parahaemolyticus cytotoxicity is regulated, in a growth rate-independent manner, by the HU proteins through regulation of a number of virulence factors, including T3SS1 gene expression. Vibrio parahaemolyticus is a Gram-negative halophilic bacterium that causes seafood-associated gastroenteritis in several countries (1-3). This organism is one of the most rapidly growing bacterial species (4, 5), with a minimal doubling time in culture of less than 10 min. The rate of growth is thought to affect the pathogenicity of V. parahaemolyticus.V. parahaemolyticus virulence factors include thermostable direct hemolysin (TDH); TDH-related hemolysin (TRH); and two separate type III secretion systems (T3SSs), T3SS1 and T3SS2 (1, 6). T3SSs are protein export systems that secrete and translocate effector proteins into the cytoplasm of host cells. Translocated effectors modify host cell function and allow pathogens to promote infection and cause disease (7,8). T3SS1 is responsible for cytotoxicity, whereas T3SS2 is related to enterotoxicity in mammalian cells (9-11). Cytotoxicity following V. parahaemolyticus infection is due primarily to the activity of the T3SS1 effector e...

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Hfq regulates the expression of the thermostable direct hemolysin gene in Vibrio parahaemolyticus

Cited by 34 publications

References 49 publications

Transcriptomic profiling of the oyster pathogen Vibrio splendidus opens a window on the evolutionary dynamics of the small RNA repertoire in the Vibrio genus

Transcriptomic profiling of the oyster pathogen Vibrio splendidus opens a window on the evolutionary dynamics of the small RNA repertoire in the Vibrio genus

Hfq regulates anti-oxidative ability in Vibrio parahaemolyticus

DNA-Binding Protein HU Coordinates Pathogenicity in Vibrio parahaemolyticus

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