HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 29, 20372-20382, July 18, 2008

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 283/29/20372    most recent M801065200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Watanabe, S. Articles by Makino, K. Search for Related Content PubMed PubMed Citation Articles by Watanabe, S. Articles by Makino, K. Social Bookmarking                      What's this?

Eukaryotic and Bacterial Gene Clusters Related to an Alternative Pathway of Nonphosphorylated L-Rhamnose Metabolism^*

Seiya Watanabe^¶1, Masayuki Saimura, and Keisuke Makino^¶||

From the Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, the New Energy and Industrial Technology Development Organization Gokasho, Uji, Kyoto 611-0011, ^¶CREST, Japan Science and Technology Agency, Gokasho, Uji, Kyoto 611-0011, and ^||Innovative Collaboration Center, Kyoto University, Yoshidahonmachi, Sakyo-ku, Kyoto 606-8501, Japan

The Entner-Doudoroff (ED) pathway is a classic central pathway of D-glucose metabolism in all three phylogenetic domains. On the other hand, Archaea and/or bacteria possess several modified versions of the ED pathway, in which nonphosphorylated intermediates are involved. Several fungi, including Pichia stipitis and Debaryomyces hansenii, possess an alternative pathway of L-rhamnose metabolism, which is different from the known bacterial pathway. Gene cluster related to this hypothetical pathway was identified by bioinformatic analysis using the metabolic enzymes involved in analogous sugar pathways to the ED pathway. Furthermore, the homologous gene cluster was found not only in many other fungi but also several bacteria, including Azotobacter vinelandii. Four putative metabolic genes, LRA1-4, were cloned, overexpressed in Escherichia coli, and purified. Substrate specificity and kinetic analysis revealed that nonphosphorylated intermediates related to L-rhamnose are significant active substrates for the purified LRA1-4 proteins. Furthermore, L-2-keto-3-deoxyrhamnonate was structurally identified as both reaction products of dehydration by LRA3 and aldol condensation by LRA4. These results suggested that the LRA1-4 genes encode L-rhamnose 1-dehydrogenase, L-rhamnono--lactonase, L-rhamnonate dehydratase, and L-KDR aldolase, respectively, by which L-rhamnose is converted into pyruvate and L-lactaldehyde through analogous reaction steps to the ED pathway. There was no evolutionary relationship between L-KDR aldolases from fungi and bacteria.

Received for publication, February 8, 2008 , and in revised form, May 12, 2008.

^* This work was supported by Grant-in-aid for Young Scientists (B) 18760592, the Ministry of Education, Culture, Sports, Science, and Technology of Japan (to S. W.), the Fermentation and Metabolism Research Foundation, the Japan Bioindustry Association (to S. W.), New Energy and Industrial Technology Development Organization (to S. W.), and CREST, Japan Science and Technology Agency (to K. M.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Tables SI-SIII and Figs. S1-S4.

¹ To whom correspondence should be addressed. Tel.: 81-774-38-3596; Fax: 81-774-38-3524; E-mail: irab{at}iae.kyoto-u.ac.jp.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?