Characterisation of a type IV pilus produced by Aeromonas caviae

Kirov, SM; Sanderson, K; Dickson, Tracey C.

doi:10.1099/00222615-47-6-527

Cited by 18 publications

(21 citation statements)

References 25 publications

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“…The ®ndings of the present study are at variance with that described recently of type IV pili in A. caviae strains isolated from clinical sources in Australia [32], possibly because they are from a different geographic location [6]. Furthermore, it is possible that, if ®lamentous structures are expressed on the cell surface of A. caviae, they exist only in very small numbers under the conditions tested here.…”

Section: Discussioncontrasting

confidence: 55%

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Identification of a 43-kDa outer-membrane protein as an adhesin in Aeromonas caviae

Rocha-de-Souza¹,

Colombo²,

Hirata³

et al. 2001

Journal of Medical Microbiology

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Aeromonas spp. are associated with intestinal and extra-intestinal infections. However, the virulence factors of A. caviae remain, for the most part, poorly known. This study examined the interactions involved in the adherence of A. caviae isolates Ae56, Ae391 and Ae398 to HEp-2 cells. All strains expressed high levels of aggregative adherence. Maximum adhesion occurred with bacteria grown at 228C, but transmission electron microscopy did not reveal the presence of ®mbrial structures on the bacterial cell surface. Outer-membrane proteins (OMPs) extracted from isolate Ae398, grown at 228C and 378C, showed similar SDS-PAGE protein pro®les. Most proteins were < 60 kDa. A major 43-kDa protein was seen only in the boiled OMP extract. The biotinylated 43-kDa protein bound speci®cally to HEp-2 cells. Microbeads coated with the 43-kDa protein were also adherent to HEp-2 cells, and anti-43-kDa protein antibody blocked adherence of 43-kDa protein-coated latex beads. These data suggest that the 43-kDa OMP functions as an adhesin in A. caviae.

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Section: Discussioncontrasting

confidence: 55%

“…Furthermore, it is possible that, if ®lamentous structures are expressed on the cell surface of A. caviae, they exist only in very small numbers under the conditions tested here. On the other hand, adhesion of the Australian A. caviae strains to HEp-2 cells was only in part mediated by ®lamentous structures [32].…”

Section: Discussionmentioning

confidence: 99%

Identification of a 43-kDa outer-membrane protein as an adhesin in Aeromonas caviae

Rocha-de-Souza¹,

Colombo²,

Hirata³

et al. 2001

Journal of Medical Microbiology

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“…Aeromonas spp. also possess type IV pili and bundle-forming pili, the latter of which has been shown to be associated with gastroenteritis (23,29).…”

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confidence: 99%

Molecular and Functional Characterization of a ToxR-Regulated Lipoprotein from a Clinical Isolate of Aeromonas hydrophila

et al. 2006

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Human diseases caused by species of Aeromonas have been classified into two major groups: septicemia and gastroenteritis. In this study, we reported the molecular and functional characterization of a new virulence factor, ToxR-regulated lipoprotein, or TagA, from a diarrheal isolate, SSU, of Aeromonas hydrophila. The tagA gene of A. hydrophila exhibited 60% identity with that of a recently identified stcE gene from Escherichia coli O157:H7, which encoded a protein (StcE) that provided serum resistance to the bacterium and prevented erythrocyte lysis by controlling classical pathway of complement activation by cleaving the complement C1-esterase inhibitor (C1-INH). We purified A. hydrophila TagA as a histidine-tagged fusion protein (rTagA) from E. coli DE3 strain using a T7 promoter-based pET30 expression vector and nickel affinity column chromatography. rTagA cleaved C1-INH in a time-dependent manner. The tagA isogenic mutant of A. hydrophila, unlike its corresponding wild-type (WT) or the complemented strain, was unable to cleave C1-INH, which is required to potentiate the C1-INH-mediated lysis of host and bacterial cells. We indeed demonstrated colocalization of C1-INH and TagA on the bacterial surface by confocal fluorescence microscopy, which ultimately resulted in increased serum resistance of the WT bacterium. Likewise, we delineated the role of TagA in contributing to the enhanced ability of C1-INH to inhibit the classical complement-mediated lysis of erythrocytes. Importantly, we provided evidence that the tagA mutant was significantly less virulent in a mouse model of infection (60%) than the WT bacterium at two 50% lethal doses, which resulted in 100% mortality within 48 h. Taken together, our data provided new information on the role of TagA as a virulence factor in bacterial pathogenesis. This is the first report of TagA characterization from any species of Aeromonas.Aeromonas hydrophila represents one of the most predominant species within the family Aeromonadaceae that leads to human diseases, such as gastroenteritis, wound infections, and septicemia (21). These pathogens have been isolated from a wide variety of food and water sources and are being recovered with increasing frequency from patients with traveler's diarrhea (9,19,21). Resistance of Aeromonas spp. to water chlorination and to multiple antibiotics has resulted in this organism being placed on the "Contaminant Candidate List" by the Environmental Protection Agency (9). These ubiquitous bacteria produce a large number of virulence factors, many of which have been linked to Aeromonas-associated pathogenesis. Among them are matrix-binding proteins, elastases, proteases, cytotonic and cytotoxic enterotoxins, hemolysins, aldolase, chitinase, lipases/phospholipases, and the ability to form a capsule-like outer layer (10,30,35,45). Aeromonas spp. also possess type IV pili and bundle-forming pili, the latter of which has been shown to be associated with gastroenteritis (23, 29).Our laboratory purified and extensively characterized the cytotoxi...

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“…In immuno-compromised individuals, some of the more serious complications associated with A. hydrophila infections are cellulitis, myonecrosis, and ecthyma gangrenosum, which often are fatal (2, 36). A variety of virulence factors/mechanisms, such as the surface layer, capsule, different forms of pili (e.g., type IV [Tap] and bundle-forming pili), toxins, quorum sensing, biofilm formation and, more recently, the type III secretion system (T3SS), were identified in various Aeromonas species that are involved in the pathogenesis of Aeromonas infections (10,11,40,52,75,82,89). Currently, the set of virulence factors crucial in causing human diseases is unknown in this pathogen and, therefore, the search for new virulence factors and their regulation must continue.…”

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confidence: 99%

DNA Adenine Methyltransferase Influences the Virulence of Aeromonas hydrophila

et al. 2006

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Among the various virulence factors produced by Aeromonas hydrophila, a type II secretion system (T2SS)-secreted cytotoxic enterotoxin (Act) and the T3SS are crucial in the pathogenesis of Aeromonas-associated infections. Our laboratory molecularly characterized both Act and the T3SS from a diarrheal isolate, SSU of A. hydrophila, and defined the role of some regulatory genes in modulating the biological effects of Act. In this study, we cloned, sequenced, and expressed the DNA adenine methyltransferase gene of A. hydrophila SSU (dam AhSSU ) in a T7 promoter-based vector system using Escherichia coli ER2566 as a host strain, which could alter the virulence potential of A. hydrophila. Recombinant Dam, designated as M.AhySSUDam, was produced as a histidine-tagged fusion protein and purified from an E. coli cell lysate using nickel affinity chromatography. The purified Dam had methyltransferase activity, based on its ability to transfer a methyl group from S-adenosyl-L-methionine to N 6 -methyladenine-free lambda DNA and to protect methylated lambda DNA from digestion with DpnII but not against the DpnI restriction enzyme. The dam gene was essential for the viability of the bacterium, and overproduction of Dam in A. hydrophila SSU, using an arabinose-inducible, P BAD promoter-based system, reduced the virulence of this pathogen. Specifically, overproduction of M.AhySSUDam decreased the motility of the bacterium by 58%. Likewise, the T3SS-associated cytotoxicity, as measured by the release of lactate dehydrogenase enzyme in murine macrophages infected with the Dam-overproducing strain, was diminished by 55% compared to that of a control A. hydrophila SSU strain harboring the pBAD vector alone. On the contrary, cytotoxic and hemolytic activities associated with Act as well as the protease activity in the culture supernatant of a Dam-overproducing strain were increased by 10-, 3-, and 2.4-fold, respectively, compared to those of the control A. hydrophila SSU strain. The Dam-overproducing strain was not lethal to mice (100% survival) when given by the intraperitoneal route at a dose twice that of the 50% lethal dose, which within 2 to 3 days killed 100% of the animals inoculated with the A. hydrophila control strain. Taken together, our data indicated alteration of A. hydrophila virulence by overproduction of Dam.Aeromonas hydrophila is both a human and an animal pathogen, and the diseases associated with this bacterium in humans include gastroenteritis, wound infections, and septicemia (36, 88). In immuno-compromised individuals, some of the more serious complications associated with A. hydrophila infections are cellulitis, myonecrosis, and ecthyma gangrenosum, which often are fatal (2, 36). A variety of virulence factors/mechanisms, such as the surface layer, capsule, different forms of pili (e.g., type IV [Tap] and bundle-forming pili), toxins, quorum sensing, biofilm formation and, more recently, the type III secretion system (T3SS), were identified in various Aeromonas species that are involved in the pathogenesis...

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Characterisation of a type IV pilus produced by Aeromonas caviae

Cited by 18 publications

References 25 publications

Identification of a 43-kDa outer-membrane protein as an adhesin in Aeromonas caviae

Identification of a 43-kDa outer-membrane protein as an adhesin in Aeromonas caviae

Molecular and Functional Characterization of a ToxR-Regulated Lipoprotein from a Clinical Isolate of Aeromonas hydrophila

DNA Adenine Methyltransferase Influences the Virulence of Aeromonas hydrophila

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