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J Bacteriol, May 1998, p. 2782-2787, Vol. 180, No. 10
Department of Biological Sciences, Northern
Illinois University, DeKalb, Illinois 60115
Received 23 June 1997/Accepted 18 March 1998
A key reaction in the biosynthesis of menaquinone involves the
conversion of the soluble bicyclic naphthalenoid compound
1,4-dihydroxy-2-naphthoic acid (DHNA) to the membrane-bound
demethylmenaquinone. The enzyme catalyzing this reaction,
DHNA-octaprenyltransferase, attaches a 40-carbon side chain to DHNA.
The menA gene encoding this enzyme has been cloned and
localized to a 2.0-kb region of the Escherichia coli genome
between cytR and glpK. DNA sequence analysis of
the cloned insert revealed a 308-codon open reading frame (ORF), which by deletion analyses was shown to restore anaerobic growth of a
menA mutant. Reverse-phase high-performance liquid
chromatography analysis of quinones extracted from the
orf-complemented cells independently confirmed the
restoration of menaquinone biosynthesis, and similarly, analyses of
isolated cell membranes for DHNA octaprenyltransferase activity
confirmed the introduction of the menA product into the orf-complemented menA mutant. The validity of
an ORF-associated putative promoter sequence was confirmed by primer
extension analyses.
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Menaquinone (Vitamin K2) Biosynthesis:
Localization and Characterization of the menA Gene from
Escherichia coli
*
Corresponding author. Mailing address: Department of
Biological Sciences, Northern Illinois University, DeKalb, IL
60115-2861. Phone: (815) 753-7803. Fax: (815) 753-0461. E-mail:
rmeganathan{at}niu.edu.
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