<i>C</i>-Methylation of <i>S</i>-adenosyl-L-Methionine Occurs Prior to Cyclopropanation in the Biosynthesis of 1-Amino-2-Methylcyclopropanecarboxylic Acid (Norcoronamic Acid) in a Bacterium
Chitose Maruyama,
Yukiko Chinone,
Shusuke Sato,
Fumitaka Kudo,
Kosuke Ohsawa,
Junya Kubota,
Junko Hashimoto,
Ikuko Kozone,
Takayuki Doi,
Kazuo Shin-ya,
Tadashi Eguchi,
Yoshimitsu Hamano
Affiliations
Chitose Maruyama
Department of Bioscience, Fukui Prefectural University, 4-1-1 Yoshida-Gun, Fukui 910-1195, Japan
Yukiko Chinone
Department of Bioscience, Fukui Prefectural University, 4-1-1 Yoshida-Gun, Fukui 910-1195, Japan
Shusuke Sato
Department of Chemistry, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
Fumitaka Kudo
Department of Chemistry, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
Kosuke Ohsawa
Graduate School of Life Sciences, Tohoku University, 6-3 Aza-aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
Junya Kubota
Graduate School of Life Sciences, Tohoku University, 6-3 Aza-aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
Junko Hashimoto
Japan Biological Informatics Consortium (JBIC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
Ikuko Kozone
Japan Biological Informatics Consortium (JBIC), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
Takayuki Doi
Graduate School of Life Sciences, Tohoku University, 6-3 Aza-aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
Kazuo Shin-ya
National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan
Tadashi Eguchi
Department of Chemistry, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
Yoshimitsu Hamano
Department of Bioscience, Fukui Prefectural University, 4-1-1 Yoshida-Gun, Fukui 910-1195, Japan
Many pharmacologically important peptides are bacterial or fungal in origin and contain nonproteinogenic amino acid (NPA) building blocks. Recently, it was reported that, in bacteria, a cyclopropane-containing NPA 1-aminocyclopropanecarboxylic acid (ACC) is produced from the L-methionine moiety of S-adenosyl-L-methionine (SAM) by non-canonical ACC-forming enzymes. On the other hand, it has been suggested that a monomethylated ACC analogue, 2-methyl-ACC (MeACC), is derived from L-valine. Therefore, we have investigated the MeACC biosynthesis by identifying a gene cluster containing bacterial MeACC synthase genes. In this gene cluster, we identified two genes, orf29 and orf30, which encode a cobalamin (B12)-dependent radical SAM methyltransferase and a bacterial ACC synthase, respectively, and were found to be involved in the MeACC biosynthesis. In vitro analysis using their recombinant enzymes (rOrf29 and rOrf30) further revealed that the ACC structure of MeACC was derived from the L-methionine moiety of SAM, rather than L-valine. In addition, rOrf29 was found to catalyze the C-methylation of the L-methionine moiety of SAM. The resulting methylated derivative of SAM was then converted into MeACC by rOrf30. Thus, we demonstrate that C-methylation of SAM occurs prior to cyclopropanation in the biosynthesis of a bacterial MeACC (norcoronamic acid).
