A pyridoxal-phosphate protein. The enzyme, purified from the bacterium Paracoccus denitrificans IFO 13301, is strictly D-specific as to the alpha-position of the substrate, but accepts both the threo and erythro forms at the beta-position. The erythro form is a far better substrate (about 100-fold). The enzyme can also accept D-allothreonine, D-threonine, erythro-3-phenyl-D-serine and threo-3-phenyl-D-serine. Different from EC 18.104.22.168, erythro-3-hydroxy-L-aspartate aldolase. Requires a divalent cation, such as Mg2+, Mn2+ or Co2+.