Serine hydroxymethyltransferase (SHMT) belongs to the a-family of pyridoxal 5¢-phosphate-dependent enzymes and catalyzes the reversible conversion of l-Ser and tetrahydrofolate to Gly and 5,10-methylene tetrahydrofolate. 5,10-Methylene tetrahydrofolate serves as a source of one-carbon fragment in many biological processes.