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Control Mechanism for Carbon‐Chain Length in Polyunsaturated Fatty‐Acid Synthases
Author(s) -
Hayashi Shohei,
Naka Mai,
Ikeuchi Kenshin,
Ohtsuka Makoto,
Kobayashi Kota,
Satoh Yasuharu,
Ogasawara Yasushi,
Maruyama Chitose,
Hamano Yoshimitsu,
Ujihara Tetsuro,
Dairi Tohru
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201900771
Subject(s) - polyunsaturated fatty acid , docosahexaenoic acid , biochemistry , biosynthesis , eicosapentaenoic acid , chemistry , elongation , fatty acid , atp synthase , enzyme , materials science , metallurgy , ultimate tensile strength
Polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are essential fatty acids. PUFA synthases are composed of three to four subunits and each create a specific PUFA without undesirable byproducts. However, detailed biosynthetic mechanisms for controlling final product profiles have been obscure. Here, the bacterial DHA and EPA synthases were carefully dissected by in vivo and in vitro experiments. In vitro analysis with two KS domains (KS A and KS C ) and acyl‐acyl carrier protein (ACP) substrates showed that KS A accepted short‐ to medium‐chain substrates while KS C accepted medium‐ to long‐chain substrates. Unexpectedly, condensation from C 18 to C 20 , the last elongation step in EPA biosynthesis, was catalyzed by KS A domains in both EPA and DHA synthases. Conversely, condensation from C 20 to C 22 , the last elongation step for DHA biosynthesis, was catalyzed by the KS C domain in DHA synthase. KS C domains therefore determine the chain lengths.