Characterization of a B-12 Trafficking Chaperone Protein From Caenorhabditis elegans

Title
Characterization of a B-12 Trafficking Chaperone Protein From Caenorhabditis elegans
Author(s)
김지회박지현
Keywords
RAY CRYSTAL-STRUCTURE; METHYLMALONIC ACIDURIA; GLUTATHIONYLCOBALAMIN; COBALAMIN; IDENTIFICATION; METABOLISM; VITAMIN-B-12; GLUTATHIONE; BINDING; HOMOCYSTINURIA
Issue Date
201501
Publisher
BENTHAM SCIENCE PUBL LTD
Citation
PROTEIN AND PEPTIDE LETTERS, v.22, no.1, pp.31 - 38
Abstract
The human B-12 trafficking chaperone protein hCblC is responsible for escorted delivery and early processing of B-12 in intracellular B-12 metabolism. In this study, we characterized a putative B-12 trafficking chaperone of Caenorhabditis elegans (cCblC), which shows 26% amino acid sequence identity with hCblC. cCblC was shown to bind B-12 with a broad specificity for the upper axial ligand, as previously observed with other homologous proteins. In addition, cCblC catalyzed glutathione (GSH)-dependent elimination of alkyl and GSH upper axial ligands from alkylcobalamins and glutathionylcobalamin (GSCbl), respectively. Dealkylation of methylcobalamin (MeCbl) generated cob(II) alamin with S-methylglutathione. Cob(I) alamin was detected as the intermediate for cob(II) alamin generation, indicating that the reaction is a nucleophilic displacement using the thiolate of GSH. Deglutathionylation of GSCbl also generated cob(II) alamin, via cob(I) alamin intermediate, with glutathione disulfide, indicating the reaction is chemically analogous with dealkylation. Cob(II) alamin generated by dealkylation and deglutathionylation was bound to cCblC in the base-off state and stable under aerobic conditions, which would be favorable for subsequent enzyme cofactor synthesis. These results demonstrate that cCblC is a B-12 trafficking chaperone of C. elegans catalyzing dealkylation and deglutathionylation via a nucleophilic displacement using the thiolate of GSH.
URI
http://hdl.handle.net/YU.REPOSITORY/33751
ISSN
0929-8665
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