Molecular and Functional Characterization of a ToxR-Regulated Lipoprotein from a Clinical Isolate of
            <i>Aeromonas hydrophila</i>

Pillai, Lakshmi; Sha, Jian; Erova, Tatiana E.; Fadl, Amin A.; Khajanchi, Bijay K.; Chopra, Ashok K.

doi:10.1128/iai.00402-06

Cited by 27 publications

(23 citation statements)

References 52 publications

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“…Through their ability to cleave O-glycoproteins, many of these peptidases have important roles in cell biology (10,12,15), have been implicated in bacterial pathogenesis (16)(17)(18), or have found use as reagents (7). Despite the functional significance of O-glycoprotein degrading peptidases, however, their mode of action on O-glycoproteins is unidentified.…”

Section: Significancementioning

confidence: 99%

Recognition of protein-linked glycans as a determinant of peptidase activity

Noach

Ficko-Blean

Pluvinage

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

137

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The vast majority of proteins are posttranslationally altered, with the addition of covalently linked sugars (glycosylation) being one of the most abundant modifications. However, despite the hydrolysis of protein peptide bonds by peptidases being a process essential to all life on Earth, the fundamental details of how peptidases accommodate posttranslational modifications, including glycosylation, has not been addressed. Through biochemical analyses and X-ray crystallographic structures we show that to hydrolyze their substrates, three structurally related metallopeptidases require the specific recognition of O-linked glycan modifications via carbohydrate-specific subsites immediately adjacent to their peptidase catalytic machinery. The three peptidases showed selectivity for different glycans, revealing protein-specific adaptations to particular glycan modifications, yet always cleaved the peptide bond immediately preceding the glycosylated residue. This insight builds upon the paradigm of how peptidases recognize substrates and provides a molecular understanding of glycoprotein degradation.

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Section: Significancementioning

confidence: 99%

Recognition of protein-linked glycans as a determinant of peptidase activity

Noach

Ficko-Blean

Pluvinage

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

137

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“…Further, this substrate could detect both metalloproteases and serine proteases, which are the two major classes of proteases produced by Aeromonas species. The substrate incubated with Dulbecco phosphate-buffered saline (DPBS) alone served as a negative control (57). AHL production.…”

Section: Colony Blot Hybridization Aeromonas Cultures (Clinical and mentioning

confidence: 99%

“…The membranes were washed twice at 68°C in 2ϫ SSC (1ϫ SSC is 0.15 M NaCl plus 0.015 M sodium citrate, pH 7.0) with 0.1% SDS for 20 min and then twice in 1ϫ SSC with 0.1% SDS for 20 min at 68°C. Subsequently, the filters were dried, and X-ray film was exposed to the filters as described previously (57).…”

Section: Colony Blot Hybridization Aeromonas Cultures (Clinical and mentioning

confidence: 99%

Distribution of Virulence Factors and Molecular Fingerprinting of Aeromonas Species Isolates from Water and Clinical Samples: Suggestive Evidence of Water-to-Human Transmission

Khajanchi

Fadl

Borchardt

et al. 2010

Appl Environ Microbiol

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136

121

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A total of 227 isolates of Aeromonas obtained from different geographical locations in the United States and different parts of the world, including 28 reference strains, were analyzed to determine the presence of various virulence factors. These isolates were also fingerprinted using biochemical identification and pulse-field gel electrophoresis (PFGE). Of these 227 isolates, 199 that were collected from water and clinical samples belonged to three major groups or complexes, namely, the A. hydrophila group, the A. caviae-A. media group, and the A. veronii-A. sobria group, based on biochemical profiles, and they had various pulsotypes. When virulence factor activities were examined, Aeromonas isolates obtained from clinical sources had higher cytotoxic activities than isolates obtained from water sources for all three Aeromonas species groups. Likewise, the production of quorum-sensing signaling molecules, such as N-acyl homoserine lactone, was greater in clinical isolates than in isolates from water for the A. caviae-A. media and A. hydrophila groups. Based on colony blot DNA hybridization, the heat-labile cytotonic enterotoxin gene and the DNA adenosine methyltransferase gene were more prevalent in clinical isolates than in water isolates for all three Aeromonas groups. Using colony blot DNA hybridization and PFGE, we obtained three sets of water and clinical isolates that had the same virulence signature and had indistinguishable PFGE patterns. In addition, all of these isolates belonged to the A. caviae-A. media group. The findings of the present study provide the first suggestive evidence of successful colonization and infection by particular strains of certain Aeromonas species after transmission from water to humans.

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“…Most importantly, our laboratory has described type II, type III, and type VI secretion system effector proteins that are involved in the disease state (gastroenteritis or septicemia) in animal models (11,15,17,21,32,(44)(45)(46)48). However, to better understand the full virulence potential of any pathogen, it is important to identify new pathogenic factors and/or mechanisms that could be involved in their virulence.…”

mentioning

confidence: 99%

Cold Shock Exoribonuclease R (VacB) Is Involved in Aeromonas hydrophila Pathogenesis

Erova¹,

Kosykh

Fadl³

et al. 2008

J Bacteriol

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In this study, we cloned and sequenced a virulence-associated gene (vacB) from a clinical isolate SSU of Aeromonas hydrophila. We identified this gene based on our recently annotated genome sequence of the environmental isolate ATCC 7966 T of A. hydrophila and the vacB gene of Shigella flexneri. The A. hydrophila VacB protein contained 798 amino acid residues, had a molecular mass of 90.5 kDa, and exhibited an exoribonuclease (RNase R) activity. The RNase R of A. hydrophila was a cold-shock protein and was required for bacterial growth at low temperature. The vacB isogenic mutant, which we developed by homologous recombination using marker exchange mutagenesis, was unable to grow at 4°C. In contrast, the wild-type (WT) A. hydrophila exhibited significant growth at this low temperature. Importantly, the vacB mutant was not defective in growth at 37°C. The vacB mutant also exhibited reduced motility, and these growth and motility phenotype defects were restored after complementation of the vacB mutant. The A. hydrophila RNase R-lacking strain was found to be less virulent in a mouse lethality model (70% survival) when given by the intraperitoneal route at as two 50% lethal doses (LD 50 ). On the other hand, the WT and complemented strains of A. hydrophila caused 80 to 90% of the mice to succumb to infection at the same LD 50 dose. Overall, this is the first report demonstrating the role of RNase R in modulating the expression of A. hydrophila virulence.A human diarrheal isolate SSU of Aeromonas hydrophila possesses various pathogenic mechanisms that contribute to the overall virulence of this bacterium in the host. Most importantly, our laboratory has described type II, type III, and type VI secretion system effector proteins that are involved in the disease state (gastroenteritis or septicemia) in animal models (11,15,17,21,32,(44)(45)(46)48). However, to better understand the full virulence potential of any pathogen, it is important to identify new pathogenic factors and/or mechanisms that could be involved in their virulence. This is crucial since the expression of different virulence genes could be contributing factors leading to disease depending upon the anatomical niche where the organisms colonize and the environment in those regions which dictates the differential expression of genes (18).Studies by Tobe et al. (50) identified a novel chromosomal gene, vacB, which was required for the production of S. flexneri virulence factors (e.g., IpaB, IpaC, IpaD, and VirG) from the large plasmid (230 kb) of this microorganism. More recently, it was shown that the vacB gene in S. flexneri and Escherichia coli strains encoded the 3Ј-5Ј exoribonuclease RNase R (10). The deduced size of VacB (virulence-associated) protein is approximately 92 kDa, and it is located at 95 min on the E. coli chromosome, a position consistent with the earlier mapping studies of the gene encoding RNase R (10). These investigators provided evidence that RNase R has an essential cell function, in addition to its role in bacterial virulence, an...

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

Cited by 27 publications

References 52 publications

Recognition of protein-linked glycans as a determinant of peptidase activity

Recognition of protein-linked glycans as a determinant of peptidase activity

Distribution of Virulence Factors and Molecular Fingerprinting of Aeromonas Species Isolates from Water and Clinical Samples: Suggestive Evidence of Water-to-Human Transmission

Cold Shock Exoribonuclease R (VacB) Is Involved in Aeromonas hydrophila Pathogenesis

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