2Department of Pharmacognosy, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand; fax: +662-254-5195; E-mail: email@example.com
3Laboratory of Applied Microbiology, Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan; fax: +81-83-933-5859; E-mail: firstname.lastname@example.org
4Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, Senbaru, Nishihara-cho, Okinawa 903-0213, Japan; fax: +81-98-895-8805; E-mail: email@example.com
* To whom correspondence should be addressed.
Received May 12, 2009; Revision received June 4, 2009
The quinate dehydrogenase (QDH) from Gluconobacter oxydans IFO3244 exhibits high affinity for quinate, suggesting its application in shikimate production. Nucleotide sequence analysis of the qdh gene revealed a full-length of 2475-bp encoding an 824-amino acid protein. The qdh gene has the unusual TTG translation initiation codon. Conserved regions and a signature sequence for the quinoprotein family were observed. Phylogenetic analysis demonstrated relatedness of QDH from G. oxydans to other quinate/shikimate dehydrogenases with the highest similarity (56%) with that of Acinetobacter calcoaceticus ADP1 and lower similarity (36%) with a membrane-bound glucose dehydrogenase of Escherichia coli. The function of the gene coding for QDH was confirmed by heterologous gene expression in pyrroloquinoline quinone-synthesizing Pseudomonas putida HK5.
KEY WORDS: quinate dehydrogenase gene, heterologous gene expression, Gluconobacter oxydans, pyrroloquinoline quinone