The enzyme is part of the biosynthetic pathway of phenolphthiocerol, a lipid that serves as a virulence factor of pathogenic mycobacteria. It catalyses the elongation of 4-hydroxybenzoate that is loaded on its acyl-carrier domain to form (4-hydroxyphenyl)alkanoate intermediates. The enzyme adds either 8 or 9 malonyl-CoA units, resulting in formation of 17-(4-hydroxyphenyl)heptadecanoate or 19-(4-hydroxyphenyl)nonadecanoate, respectively. As the enzyme lacks a thioesterase domain , the product remains loaded on the acyl-carrier domain at the end of catalysis, and has to be hydrolysed by an as-yet unknown mechanism.
Constant P, Perez E, Malaga W, Laneelle MA, Saurel O, Daffe M, Guilhot C
Role of the pks15/1 gene in the biosynthesis of phenolglycolipids in the Mycobacterium tuberculosis complex. Evidence that all strains synthesize glycosylated p-hydroxybenzoic methyl esters and that strains devoid of phenolglycolipids harbor a frameshift mutation in the pks15/1 gene.