Genome Property Definition Page

Namehomocysteine regeneration from S-adenosylhomocysteine
DescriptionS-adenosylmethionine (SAM) is used in cells as a methyl donor by a large guild of methyltransferases, leaving S-adenosylhomocysteine (SAH). SAH can be cleaved in one step to adenosine and homocysteine by adenosylhomocysteinase (EC The homocysteine can then be used to regenerate methionine. Alternatively, it can be cleaved in two steps. First adenine is removed by adenosylhomocysteine nucleosidase (EC, a fascinating enzyme that, with a different bound cofactor, acts instead in the pathway of methionine salvage from methylthioadenosine - see TIGR01704) to leave S-ribosylhomocysteine. Next, S-ribosylhomocysteinase acts to produce homocysteine and 4,5-dihydroxypentan-2,3-dione, which cyclizes spontaneously and binds borate to become autoinducer-2 (AI-2), a quorum-sensing molecule produced and recognized by a wide range of bacteria. This property represents the presence at least one of these two mechanisms to regenerate homocysteine.
JCVI RoleSulfur metabolism
Parent PropertyGenProp0731: amino acid metabolism

Step NameStep NumRequiredEvidence (Method)Evidence Go Terms
SAH to homocysteineSAH_clvYESTIGR00936 (HMM): adenosylhomocysteinaseGenProp0757 (GENPROP): quorum-sensing, autoinducer-2 system
methionine adenosyltransferaseSAM_synYESTIGR01034 (HMM): methionine adenosyltransferase
PF01941 (HMM): S-adenosylmethionine synthetase

Parent Properties
GenProp0731amino acid metabolism

Sibling Properties
GenProp0126amino acid biosynthesis
GenProp0733amino acid salvage
GenProp0734amino acid catabolism