Mediates the conversion of 2-dehydro-3-deoxy-L-galactonate to pyruvate and L-glyceraldehyde in D-galacturonate catabolic process. 2-dehydro-3-deoxy-L-galactonate = L-glyceraldehyde + pyruvate Carbohydrate acid metabolism. Cells are unable to grow on D-galacturonate. Belongs to the DapA family.