Involved in the biosynthesis of 2-methyl-3-n-amyl-pyrrole (MAP), one of the terminal products involved in the biosynthesis of the red antibiotic prodigiosin (Pig). Catalyzes the decarboxylation of pyruvate, followed by the modification of the resulting two-carbon fragment acetaldehyde at the C3 position of the 2-octenal (1,2-addition of acetaldehyde) giving 3-acetyloctanal. In vitro, it can act on a number of alpha,beta-unsaturated carbonyl compounds, including aldehydes and ketones, and can catalyze both 1,2-addition and Stetter-type 1,4-addition depending on the substrate. (2E)-octenal + H(+) + pyruvate = (S)-3-acetyloctanal + CO2 Antibiotic biosynthesis; prodigiosin biosynthesis. Belongs to the TPP enzyme family.