Skip Navigation



Journal of Biochemistry Advance Access published online on January 16, 2009
Journal of Biochemistry, doi:10.1093/jb/mvp005
This Article
Right arrow Advance Access manuscript (PDF)
Right arrow Supplementary Data
Right arrow All Versions of this Article:
145/4/525    most recent
mvp005v2
mvp005v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Request Permissions
Google Scholar
Right arrow Articles by Yokochi, N.
Right arrow Articles by Yagi, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Yokochi, N.
Right arrow Articles by Yagi, T.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The authors 2009. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Gene Identification and Characterization of 5-Formyl-3-hydroxy-2-methylpyridine 4-Carboxylic Acid 5-Dehydrogenase, an NAD+-dependent Dismutase

Nana Yokochi1,{dagger}, Yu Yoshikane1,{dagger}, Sora Matsumoto1,{dagger}, Manaho Fujisawa1, Kouhei Ohnishi2 and Toshiharu Yagi1,*

1Department of Bioresources Science, Faculty of Agriculture, and 2Research Institute of Molecular Genetics, Kochi University, Monobe-Otsu 200, Nankoku, Kochi 783-8502, Japan

*To whom correspondence should be addressed: Toshiharu Yagi: Tel: +81 88 864 5191, Fax: +81 88 864 5191, E-mail: yagito{at}kochi-u.ac.jp

Received October 23, 2009; Accepted January 7, 2009


  Abstract

A chromosomal gene, mlr6793, in Mesorhizobium loti was identified as the gene encoding 5-formyl-3-hydroxy-2-methylpyridine 4-carboxylic acid (FHMPC) dehydrogenase (dismutase) involved in the degradation pathway for pyridoxine (vitamin B6). The homogenously purified recombinant enzyme has a molecular mass of 59.1 kDa and is a homo-dimeric protein. FHMPC dehydrogenase catalyzes practically irreversible oxidation (kcat = 204 s-1) of FHMPC (Km = 48.2 µM) by NAD+ (Km = 34.3 µM) to 3-hydroxy-2-methyl-pyridine 4, 5-dicarboxylic acid (HMPDC), and practically irreversible reduction (kcat = 217 s-1) of FHMPC (Km = 24.9 µM) by NADH (Km = 12.4 µM) to 4-pyridoxic acid. When the enzyme reaction was started with the combination of FHMPC and NAD+ or that of FHMPC and NADH, HMPDC and 4-pyridoxic acid were produced in an almost equimolar ratio throughout the reaction. FHMPC dehydrogenase belongs to the 3-hydroxyacyl-CoA dehydrogenase family with 31% identity with the human enzyme: it has probable catalytic diad residues, i.e. His137 and Glu149. The H137L mutant enzyme showed no measurable activity. The E149Q one was stable in contrast to the corresponding human 3-hydroxyacyl-CoA dehydrogenase mutant, and showed unique pH optima depending on the cosubstrates used for the reaction.

Key Words: 5-formyl-3-hydroxy-2-methylpyridine 4-carboxylic acid (FHMPC) dehydrogenase, NAD+-dependent dismutase, Mesorhizobium loti, vitamin B6-degradation pathway

{dagger} These authors contributed equally to this study.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.