-!- Involved in the dissociated (or type II) fatty-acid biosynthesis system that occurs in plants and bacteria. -!- In contrast to EC 2.3.1.41 and EC 2.3.1.179, this enzyme specifically uses CoA thioesters rather than acyl-ACP as the primer. -!- In addition to the above reaction, the enzyme can also catalyze the reaction of EC 2.3.1.38, but to a much lesser extent. -!- Responsible for initiating both straight- and branched-chain fatty- acid biosynthesis, with the substrate specificity in an organism reflecting the fatty-acid composition found in that organism. -!- For example, Streptococcus pneumoniae, a Gram-positive bacterium, is able to use both straight- and branched-chain (C4--C6) acyl-CoA primers whereas Escherichia coli, a Gram-negative organism, uses primarily short straight-chain acyl CoAs, with a preference for acetyl-CoA.