Catalyzes the retro-aldol cleavage of 4-hydroxy-2-oxopentanoate to pyruvate and acetaldehyde. Is involved in the meta-cleavage pathway for the degradation of aromatic compounds. (S)-4-hydroxy-2-oxopentanoate = acetaldehyde + pyruvate Aromatic compound metabolism; 3-phenylpropanoate degradation. Interacts with MhpF. Belongs to the 4-hydroxy-2-oxovalerate aldolase family.