To provide the subject enzyme enabling industrially advantageous production of 4(R)-hydroxy-2-ketoglutaric acid, etc., useful as a synthetic raw material for pharmaceuticals, etc.

A DNA coding for e.g. 4(R)-hydroxy-2-ketoglutaric acid aldolase having the amino acid sequence of the formula, collectable from Bacillus sp. DC187 strain (FERM BP-4646), etc., and catalyzing the reaction to exclusively produce 4(R)-hydroxy-2-ketoglutaric acid from glyoxylic acid and pyruvic acid without forming 4(S)-hydroxy-2-ketoglutaric acid is introduced into a host cell via a vector to obtain a transformant. Subject enzyme produced by the culture of the transformant is made to react with glyoxylic acid and pyruvic acid in an aqueous medium to obtain 4(R)-hydroxy-2-ketoglutaric acid. 4(R)-hydroxy-L- glutamic acid and 4(R)-hydroxy-L-proline are produced by using the aqueous medium containing the transformant, an amino group donor, a carbohydrate and glyoxylic acid.