Menaquinone (vitamin K2) biosynthesis: localization and characterization of the menA gene from Escherichia coli.
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.
Suvarna
K
K
Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois 60115, USA.
Stevenson
D
D
Meganathan
R
R
Hudspeth
M E
ME
D019883:Alkyl and Aryl Transferases / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009284:Naphthols / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014812:Vitamin K / Q000096:biosynthesis*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D009284:Naphthols; D014812:Vitamin K; C024023:1,4-dihydroxy-2-naphthoic acid; D019883:Alkyl and Aryl Transferases; C021386:4-hydroxybenzoate polyprenyltransferase; C112258:MenA protein, E coli