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Molecular modelling of urease accessory interaction proteins of Helicobacter Pylori J 99 and predicting an interruption in interaction by Vigna radiata Defensins.

ABSTRACT: Helicobacter pylori is the major causative agent of Gastric carcinoma. Significance of the urease accessory interaction proteins are emphasized in colonization of human gastric mucosa and efficient infection of H. pylori. Here an attempt is made to explore the structure and properties of urease accessory interaction proteins from Helicobacter pylori J 99. The proteins chosen for the study are ureH, ureI, nikR, groL and flgS based on the interaction map available from STRING database. The above mentioned proteins do not have a comprehensive three dimensional structure. Hence the models were generated using PSI-BLAST (Position Specific Iterative-Blast) and MODELLER 9V8. Physicochemical characterization encompasses pI, EC, AI, II and GRAVY. Secondary structure was predicted using PSI-PRED. Functional characterization was done by SOSUI and DISULFIND Servers and refinement of structure was done using Ramachandran plot analysis. RMS-Z values were calculated using Q-MEAN Server and CHIMERA was used for molecular simulation studies. Plant defensins from Vigna radiata are successfully docked to the modeled structures and thus interaction could be possibly prevented. These results will pave way for further selective inhibition of H. pylori colonization and in vivo survival by employing plant defensins from Vigna radiata (VrD1 & VrD2). The work will prove that plant defensins provides anticancer relief too.

SUBMITTER: Paramasivan M

PROVIDER: S-EPMC3055154 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature

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Molecular modelling of urease accessory interaction proteins of Helicobacter Pylori J 99 and predicting an interruption in interaction by Vigna radiata Defensins.

Paramasivan Manivannan M Sankaran Ganesan G Sethuraman Naveenkumar N Devadoss Daniel Selvakumar DS Thangavelu Sathiamoorthi S Gangatharan Muralitharan M

Bioinformation 20110215 10

Helicobacter pylori is the major causative agent of Gastric carcinoma. Significance of the urease accessory interaction proteins are emphasized in colonization of human gastric mucosa and efficient infection of H. pylori. Here an attempt is made to explore the structure and properties of urease accessory interaction proteins from Helicobacter pylori J 99. The proteins chosen for the study are ureH, ureI, nikR, groL and flgS based on the interaction map available from STRING database. The above m ...[more]

PMID: 21423886

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Project description:The well-studied catalytic role of urease, the Ni-dependent conversion of urea into carbon dioxide and ammonia, has been shown to protect Helicobacter pylori against the low pH environment of the stomach lumen. We hypothesized that the abundantly expressed urease protein can play another noncatalytic role in combating oxidative stress via Met residue-mediated quenching of harmful oxidants. Three catalytically inactive urease mutant strains were constructed by single substitutions of Ni binding residues. The mutant versions synthesize normal levels of urease, and the altered versions retained all methionine residues. The three site-directed urease mutants were able to better withstand a hypochlorous acid (HOCl) challenge than a ?ureAB deletion strain. The capacity of purified urease to protect whole cells via oxidant quenching was assessed by adding urease enzyme to nongrowing HOCl-exposed cells. No wild-type cells were recovered with oxidant alone, whereas urease addition significantly aided viability. These results suggest that urease can protect H. pylori against oxidative damage and that the protective ability is distinct from the well-characterized catalytic role. To determine the capability of methionine sulfoxide reductase (Msr) to reduce oxidized Met residues in urease, purified H. pylori urease was exposed to HOCl and a previously described Msr peptide repair mixture was added. Of the 25 methionine residues in urease, 11 were subject to both oxidation and to Msr-mediated repair, as identified by mass spectrometry (MS) analysis; therefore, the oxidant-quenchable Met pool comprising urease can be recycled by the Msr repair system. Noncatalytic urease appears to play an important role in oxidant protection.IMPORTANCE Chronic Helicobacter pylori infection can lead to gastric ulcers and gastric cancers. The enzyme urease contributes to the survival of the bacterium in the harsh environment of the stomach by increasing the local pH. In addition to combating acid, H. pylori must survive host-produced reactive oxygen species to persist in the gastric mucosa. We describe a cyclic amino acid-based antioxidant role of urease, whereby oxidized methionine residues can be recycled by methionine sulfoxide reductase to again quench oxidants. This work expands our understanding of the role of an already acknowledged pathogen virulence factor and specifically expands our knowledge of H. pylori survival mechanisms.

Dataset Information

Molecular modelling of urease accessory interaction proteins of Helicobacter Pylori J 99 and predicting an interruption in interaction by Vigna radiata Defensins.

Publications

Molecular modelling of urease accessory interaction proteins of Helicobacter Pylori J 99 and predicting an interruption in interaction by Vigna radiata Defensins.

Similar Datasets

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