Trimethylamine-N-oxide is an important target for heart and brain diseases

Trimethylamine-N-oxide(TMAO)is a metabolite produced from dietary nutrients by the gut microbiome,which was first discovered in 2011 and used to predict the risk of car-diovascular disease[1].The precursors of TMAO,including phosphatidylcholine[1],choline[2],and L-carnitine[3],are commonly found in cheese,red meat,seafood,egg yolks,and other foods.To date,four different microbial enzyme systems have been identified that can convert precursor substances into trimethylamine(TMA),including choline-TMA lyase(cutC/D)[4],carnitine monooxygenase(cntA/B)[5],betaine reductase,and TMAO reductase[6].In addition,yeaW/X,which is homologous to cntA/B and can utilize a variety of substrates such as choline,betaine,carnitine andγ-butyr-obetaine,can also promote the synthesis of TMA.The coop-eration between yeaW/X and cutC/D was the most well studied[7].