Control Mechanism for Carbon‐Chain Length in Polyunsaturated Fatty‐Acid Synthases

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 contro...

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Published inAngewandte Chemie Vol. 131; no. 20; pp. 6677 - 6682
Main Authors Hayashi, Shohei, Naka, Mai, Ikeuchi, Kenshin, Ohtsuka, Makoto, Kobayashi, Kota, Satoh, Yasuharu, Ogasawara, Yasushi, Maruyama, Chitose, Hamano, Yoshimitsu, Ujihara, Tetsuro, Dairi, Tohru
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 13.05.2019
Subjects
Acyl carrier protein
Biosynthese
Biosynthesis
Byproducts
Chains
Chemistry
Condensates
Condensation
Docosahexaenoic acid
Domains
Eicosapentaenoic acid
Elongation
Enzyme
Fatty acids
Fettsäuren
Genexpression
Polyunsaturated fatty acids
Proteine
Substrates
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Summary: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 (KSA and KSC) and acyl‐acyl carrier protein (ACP) substrates showed that KSA accepted short‐ to medium‐chain substrates while KSC accepted medium‐ to long‐chain substrates. Unexpectedly, condensation from C18 to C20, the last elongation step in EPA biosynthesis, was catalyzed by KSA domains in both EPA and DHA synthases. Conversely, condensation from C20 to C22, the last elongation step for DHA biosynthesis, was catalyzed by the KSC domain in DHA synthase. KSC domains therefore determine the chain lengths. Vorbereitung ist alles: Synthasekomplexe der Eicosapentaensäure (EPA; C20) und Docosahexaensäure (DHA; C22) besitzen zwei Synthasedomänen, KSA und KSC, die beide in frühen bzw. späten Biosyntheseschritten agieren. Auf der letzten Synthesestufe katalysiert KSA die C18‐C20‐Elongation in der EPA‐ und DHA‐Biosynthese, während KSC die C20‐C22‐Elongation in der DHA‐Biosynthese katalysiert, was zeigt, dass KSC‐Domänen die Kettenlänge bestimmen.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201900771