Identification of a novel gene cluster participating in menaquinone (vitamin K2) biosynthesis. Cloning and sequence determination of the 2-heptaprenyl-1,4-naphthoquinone methyltransferase gene of Bacillus stearothermophilus.
We recently described the isolation and sequence analysis of a DNA region containing the genes of Bacillus stearothermophilus heptaprenyl diphosphate synthase, which catalyzes the synthesis of the prenyl side chain of menaquinone-7 of this bacterium. Sequence analyses revealed the presence of three open reading frames (ORFs), designated as ORF-1, ORF-2, and ORF-3, and the structural genes of the heptaprenyl diphosphate synthase were proved to consist of ORF-1 (heps-1) and ORF-3 (heps-2) (Koike-Takeshita, A., Koyama, T., Obata, S., and Ogura, K. (1995) J. Biol. Chem. 270, 18396-18400). The predicted amino acid sequence of ORF-2 (234 amino acids) contains a methyltransferase consensus sequence and shows a 22% identity with UbiG of Escherichia coli, which catalyzes S-adenosyl-L-methionine-dependent methylation of 2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone. These pieces of information led us to identify the ORF-2 gene product. The cell-free homogenate of the transformant of E. coli with an expression vector of ORF-2 catalyzed the incorporation of S-adenosyl-L-methionine into menaquinone-8, indicating that ORF-2 encodes 2-heptaprenyl-1,4-naphthoquinone methyltransferase, which participates in the terminal step of the menaquinone biosynthesis. Thus it is concluded that the ORF-1, ORF-2, and ORF-3 genes, designated heps-1, menG, and heps-2, respectively, form another cluster involved in menaquinone biosynthesis in addition to the cluster of menB, menC, menD, and menE already identified in the Bacillus subtilis and E. coli chromosomes.
Koike-Takeshita
A
A
Bio Research Laboratory, Toyota Motor Corporation, Toyota-cho 1, Toyota, Aichi 471-71, Japan.
Koyama
T
T
Ogura
K
K
D019883:Alkyl and Aryl Transferases; D000595:Amino Acid Sequence; D001483:Base Sequence; D002855:Chromatography, Thin Layer; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry; D001411:Geobacillus stearothermophilus; D008780:Methyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D014166:Transferases / Q000235:genetics*; D014812:Vitamin K / Q000096:biosynthesis*
D004269:DNA, Bacterial; D014812:Vitamin K; D014166:Transferases; C106093:2-heptaprenyl-1,4-naphthoquinone methyltransferase; D008780:Methyltransferases; D019883:Alkyl and Aryl Transferases; C024844:trans-hexaprenyltranstransferase