Chain length factor

Type II PKS complexes are comprised at a minimum of four types of subunits encoded by discrete open reading frames acyl carrier protein, ketosynthase a, ketosynthase p (also referred to as chain length factor ), and a malonyl CoA acyltransferase responsible for loading acyl-CoA extender units on to the acyl carrier protein subunit (34 Fig. 4). Additional subunits containing ketoreductase, cyclase, or aromatase activity may also occur in more complex type II synthases. Typically, the four core subunits (acyl carrier protein, ketosynthase a, ketosynthase p, and malonyl-CoA acyltransferase) participate in the iterative series of condensation reactions until a specified polyketide chain length is achieved, then folding and cyclization reactions yielding the final... 

These and other experiments proposed the designation of the KS as chain length factor (CLF) determinant [38]. It must be mentioned that genes coding for CLFs can not be interchanged in all cases as some of the KS-CLF combinations are not functional. 

Tang, Y., Tsai, S.C. Khosla, C. Polyketide chain length control by chain length factor. 

Latest proposal for the biosynthetic pathway to prodigiosin. KS, ketosynthase acyl carrier protein ST, seryl transferase and CLP, chain-length factor. 

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