title: Novel protective mechanism against irreversible hyperoxidation of peroxiredoxin: Nalpha-terminal acetylation of human peroxiredoxin II.
abstract: Peroxiredoxins (Prxs) are a group of peroxidases containing a cysteine thiol at their catalytic site. During peroxidase catalysis, the catalytic cysteine, referred to as the peroxidatic cysteine (C(P)), cycles between thiol (C(P)-SH) and disulfide (-S-S-) states via a sulfenic (C(P)-SOH) intermediate. Hyperoxidation of the C(P) thiol to its sulfinic (C(P)-SO(2)H) derivative has been shown to be reversible, but its sulfonic (C(P)-SO(3)H) derivative is irreversible. Our comparative study of hyperoxidation and regeneration of Prx I and Prx II in HeLa cells revealed that Prx II is more susceptible than Prx I to hyperoxidation and that the majority of the hyperoxidized Prx II formation is reversible. However, the hyperoxidized Prx I showed much less reversibility because of the formation of its irreversible sulfonic derivative, as verified with C(P)-SO(3)H-specific antiserum. In an attempt to identify the multiple hyperoxidized spots of the Prx I on two-dimensional PAGE analysis, an N-acetylated Prx I was identified as part of the total Prx I using anti-acetylated Lys antibody. Using peptidyl-Asp metalloendopeptidase (EC 3.4.24.33) peptide fingerprints, we found that N(alpha)-terminal acetylation (N(alpha)-Ac) occurred exclusively on Prx II after demethionylation. N(alpha)-Ac of Prx II blocks Prx II from irreversible hyperoxidation without altering its affinity for hydrogen peroxide. A comparative study of non-N(alpha)-acetylated and N(alpha)-terminal acetylated Prx II revealed that N(alpha)-Ac of Prx II induces a significant shift in the circular dichroism spectrum and elevation of T(m) from 59.6 to 70.9 degrees C. These findings suggest that the structural maintenance of Prx II by N(alpha)-Ac may be responsible for preventing its hyperoxidation to form C(P)-SO(3)H.
authors.affiliation: School of Biological Sciences and Technology Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Seo
authors.affiliation: School of Biological Sciences and Technology Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Jung Chae
authors.initials: JC
authors.lastname: Lim
authors.affiliation: Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: Duck-Yeon
authors.initials: DY
authors.lastname: Lee
authors.affiliation: School of Biological Sciences and Technology Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Kyung Seok
authors.initials: KS
authors.lastname: Kim
authors.affiliation: Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Piszczek
authors.affiliation: Department of Biochemistry, College of Science, Protein Network Research Center, Yonsei University, Seoul 120-749, Korea.
authors.forename: Hyung Wook
authors.initials: HW
authors.lastname: Nam
authors.affiliation: Department of Biochemistry, College of Science, Protein Network Research Center, Yonsei University, Seoul 120-749, Korea.
authors.forename: Yu Sam
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Biochemistry, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Taeho
authors.initials: T
authors.lastname: Ahn
authors.affiliation: School of Biological Sciences and Technology Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Yun
authors.affiliation: Department of Food and Nutrition and College of Veterinary Medicine Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Kanghwa
authors.initials: K
authors.lastname: Kim
authors.affiliation: Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: P Boon
authors.initials: PB
authors.lastname: Chock
authors.affiliation: School of Biological Sciences and Technology Chonnam National University, Gwangju 500-757, Korea. Electronic address: hzchae@chonnam.ac.kr.
authors.forename: Ho Zoon
authors.initials: HZ
authors.lastname: Chae
mesh_terms: D000107:Acetylation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D054464:Peroxiredoxins / Q000378:metabolism*
chemical_list: D016877:Oxidants; D006861:Hydrogen Peroxide; C515940:PRDX1 protein, human; C086065:PRDX2 protein, human; D054464:Peroxiredoxins