Catalyzes the final step in the metabolic pathway of hydroxyproline (By similarity). Involved in osmoadaptation. (4S)-4-hydroxy-2-oxoglutarate = glyoxylate + pyruvate (4R)-4-hydroxy-2-oxoglutarate = glyoxylate + pyruvate Inhibited by divalent cations. Down-regulated when grown with elevated levels of potassium chloride. Belongs to the DapA family.