Biosynthesis of Polyunsaturated Fatty Acids by Polyketide Synthases

Psychrophilic marine bacteria can produce polyunsaturated fatty acids (PUFAs; see scheme). Until recently, PUFAs were known as important metabolites exclusively produced by eukaryotes with oxygen-dependent desaturases. Surprisingly, functional analysis of a PUFA biosynthetic gene cluster from Shewanella sp. strain SCRC2738 points towards a unique mixed pathway involving a polyketide synthase.