title: Evolution of eukaryotic cysteine sulfinic acid reductase, sulfiredoxin (Srx), from bacterial chromosome partitioning protein ParB.
abstract: Sufiredoxin (Srx) is a sulfinic acid reductase, a recently identified eukaryotic enzyme, which is involved in the reduction of the hyperoxidized sulfinic acid form of the catalytic cysteine of 2-Cys peroxiredoxins (Prx). This reaction contributes to the oxidative stress response and H2O2 mediated signaling. We show that Srx has significant sequence and structural similarity to a functionally unrelated protein, ParB, a DNA-binding protein with a helix-turn-helix (HTH) domain which is involved in chromosome partitioning in bacteria. Sequence comparison and phylogenetic analysis of the Srx and ParB protein families suggest that Srx evolved via truncation of ParB, which removed the entire C-terminal half of the protein, including the HTH domain, and a substitution of cysteine for a glutamic acid in a highly conserved structural motif of ParB. The latter substitution apparently created the sulfinic acid reductase catalytic site. Evolution of a redox enzyme from a DNA-binding protein, with retention of highly significant sequence similarity, is unusual, even when compared to functional switches accompanying recruitment of other prokaryotic proteins for new functions in eukaryotes.
authors.affiliation: National Center for Biotechnology Information, National Institutes of Health, Bethesda, Maryland 20894, USA.
authors.forename: Malay K
authors.initials: MK
authors.lastname: Basu
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D020090:Chromosome Segregation; D002876:Chromosomes, Bacterial / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives* / Q000378:metabolism; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics*; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry / Q000235:genetics; D010802:Phylogeny; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D029701:Saccharomyces cerevisiae Proteins; C052883:chromosome partition proteins, bacterial; D010088:Oxidoreductases; D050862:Oxidoreductases Acting on Sulfur Group Donors; C479426:SRX1 protein, S cerevisiae; D003545:Cysteine; C013461:cysteine sulfinic acid