Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The reductive repair of oxidized methionine residues performed by methionine sulfoxide reductase is important for the gastric pathogen Helicobacter pylori to maintain persistent stomach colonization. Methionine-containing proteins that are targeted for repair by Msr were identified from whole-cell extracts (after cells were exposed to O(2) stress) by using a coimmunoprecipitation approach. Proteins identified as Msr-interacting included catalase, GroEL, thioredoxin-1 (Trx1), and site-specific recombinase; with one exception (Trx1, the reductant for Msr) all these proteins have approximately twofold higher methionine (Met) content than other proteins. These Met-rich proteins were purified and were shown to individually form a cross-linked adduct with Msr. Catalase-specific activity in an msr strain was one-half that of the parent strain; this difference was only observed under oxidative stress conditions, and the activity was restored to nearly wild-type levels by adding Msr plus dithiothreitol to msr strain extracts. In agreement with the cross-linking study, pure Msr used Trx1 but not Trx2 as a reductant. Comparative structure modeling classified the H. pylori Msr in class II within the MsrB family, like the Neisseria enzymes. Pure H. pylori enzyme reduced only the R isomer of methyl p-tolyl-sulfoxide with an apparent K(m) of 4.1 mM for the substrate. Stress conditions (peroxide, peroxynitrite, and iron starvation) all caused approximately 3- to 3.5-fold transcriptional up-regulation of msr. Neither the O(2) level during growth nor the use of background regulatory mutants had a significant effect on msr transcription. Late log and stationary phase cultures had the highest Msr protein levels and specific activity.
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PMID:Methionine sulfoxide reductase in Helicobacter pylori: interaction with methionine-rich proteins and stress-induced expression. 1688 52