Betaine-Homocysteine S-Methyl-Transferase (BHMT) Transcription is Inhibited by S-Adenosylmethionine (AdoMet)

Abstract

Betaine-homocysteine S-methyltransferase (BHMT) (EC 2.1.1.5) is a zinc metalloenzyme that is predominantly expressed in liver. This enzyme participates in homocysteine (Hcy) metabolism by catalyzing a methyl transfer from betaine to Hcy to form dimethylglycine and methionine (Met), respectively (1, 2). Understanding the mechanisms underlying the regulation of Hcy metabolism is crucial since hyperhomocysteinemia has been demonstrated to be a risk factor for the development of arteriosclerotic vascular disease (3). Our laboratory has demonstrated that BHMT expression and activity are influenced by dietary Met. We showed that BHMT expression was dramatically elevated in the livers of rats fed diets deficient in Met (4), and a further twofold increase was observed after supplementing the Met deficient diets with BHMT methyl donors (5).