Affiliation:
1. Department of Biological Chemistry, Faculty of Agriculture
2. Applied Molecular Bioscience, Graduate School of Medicine, Yamaguchi University, Yamaguchi 753-8515, Japan
Abstract
ABSTRACT
Most
Gluconobacter
species produce and accumulate 2-keto-
d
-gluconate (2KGA) and 5KGA simultaneously from
d
-glucose via GA in culture medium. 2KGA is produced by membrane-bound flavin adenine dinucleotide-containing GA 2-dehydrogenase (FAD-GADH). FAD-GADH was purified from “
Gluconobacter dioxyacetonicus
” IFO 3271, and N-terminal sequences of the three subunits were analyzed. PCR primers were designed from the N-terminal sequences, and part of the FAD-GADH genes was cloned as a PCR product. Using this PCR product, gene fragments containing whole FAD-GADH genes were obtained, and finally the nucleotide sequence of 9,696 bp was determined. The cloned sequence had three open reading frames (ORFs),
gndS
,
gndL
, and
gndC
, corresponding to small, large, and cytochrome
c
subunits of FAD-GADH, respectively. Seven other ORFs were also found, one of which showed identity to glucono-δ-lactonase, which might be involved directly in 2KGA production. Three mutant strains defective in either
gndL
or
sldA
(the gene responsible for 5KGA production) or both were constructed. Ferricyanide-reductase activity with GA in the membrane fraction of the
gndL
-defective strain decreased by about 60% of that of the wild-type strain, while in the
sldA
-defective strain, activity with GA did not decrease and activities with glycerol,
d
-arabitol, and
d
-sorbitol disappeared. Unexpectedly, the strain defective in both
gndL
and
sldA
(double mutant) still showed activity with GA. Moreover, 2KGA production was still observed in
gndL
and double mutant strains. 5KGA production was not observed at all in
sldA
and double mutant strains. Thus, it seems that “
G. dioxyacetonicus
” IFO 3271 has another membrane-bound enzyme that reacts with GA, producing 2KGA.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
35 articles.
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