title: Distinct characteristics of two 2-Cys peroxiredoxins of Vibrio vulnificus suggesting differential roles in detoxifying oxidative stress.
abstract: Peroxiredoxins (Prxs) are ubiquitous antioxidant enzymes reducing toxic peroxides. Two distinct 2-Cys Prxs, Prx1 and Prx2, were identified in Vibrio vulnificus, a facultative aerobic pathogen. Both Prxs have two conserved catalytic cysteines, C(P) and C(R), but Prx2 is more homologous in amino acid sequences to eukaryotic Prx than to Prx1. Prx2 utilized thioredoxin A as a reductant, whereas Prx1 required AhpF. Prx2 contained GGIG and FL motifs similar to the motifs conserved in sensitive Prxs and exhibited sensitivity to overoxidation. MS analysis and C(P)-SO(3)H specific immunoblotting demonstrated overoxidation of C(P) to C(P)-SO(2)H (or C(P)-SO(3)H) in vitro and in vivo, respectively. In contrast, Prx1 was robust and C(P) was not overoxidized. Discrete expression of the Prxs implied that Prx2 is induced by trace amounts of H(2)O(2) and thereby residential in cells grown aerobically. In contrast, Prx1 was occasionally expressed only in cells exposed to high levels of H(2)O(2). A mutagenesis study indicated that lack of Prx2 accumulated sufficient H(2)O(2) to induce Prx1. Kinetic properties indicated that Prx2 effectively scavenges low levels of peroxides because of its high affinity to H(2)O(2), whereas Prx1 quickly degrades higher levels of peroxides because of its high turnover rate and more efficient reactivation. This study revealed that the two Prxs are differentially optimized for detoxifying distinct ranges of H(2)O(2), and proposed that Prx2 is a residential scavenger of peroxides endogenously generated, whereas Prx1 is an occasional scavenger of peroxides exogenously encountered. Furthermore, genome sequence database search predicted widespread coexistence of the two Prxs among bacteria.
authors.affiliation: National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, and Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, South Korea.
authors.forename: Ye-Ji
authors.initials: YJ
authors.lastname: Bang
authors.forename: Man Hwan
authors.initials: MH
authors.lastname: Oh
authors.forename: Sang Ho
authors.initials: SH
authors.lastname: Choi
mesh_terms: D000595:Amino Acid Sequence; D017124:Conserved Sequence; D003545:Cysteine / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008658:Inactivation, Metabolic; D007700:Kinetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D054464:Peroxiredoxins / Q000737:chemistry / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D013879:Thioredoxins / Q000378:metabolism; D041261:Vibrio vulnificus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
chemical_list: D050505:Mutant Proteins; D013879:Thioredoxins; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins; D003545:Cysteine