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HAMAP rule MF_00563

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General rule information [?]

Accession MF_00563
Dates 4-JUN-2002 (Created)
1-JUN-2023 (Last updated, Version 41)
Name AdoHcyase
Scope(s) Bacteria
Template(s) P10760 (SAHH_RAT); P28183 (SAHH_RHOCB); Q58783 (SIHH_METJA); Q3JY79 (SAHH_BURP1); [ Recover all ]
Triggered by HAMAP; MF_00563 (Get profile general information and statistics)

Propagated annotation [?]

Identifier, protein and gene names [?]

case <OC:Methanobacteria> or <OC:Methanococci> or <OC:Methanomicrobia> or <OC:Methanopyri>
Identifier SIHH
Protein name RecName: Full=S-inosyl-L-homocysteine hydrolase;
Identifier SAHH
Protein name RecName: Full=Adenosylhomocysteinase;
AltName: Full=S-adenosyl-L-homocysteine hydrolase;
Gene name Name=ahcY;
end case

Comments [?]

case <OC:Methanobacteria> or <OC:Methanococci> or <OC:Methanomicrobia> or <OC:Methanopyri>
FUNCTIONCatalyzes the hydrolysis of S-inosyl-L-homocysteine (SIH) to L-homocysteine (Hcy) and inosine. Likely functions in a S-adenosyl-L- methionine (SAM) recycling pathway from S-adenosyl-L-homocysteine (SAH) produced from SAM-dependent methylation reactions. Can also catalyze the reverse reaction in vitro, i.e. the synthesis of SIH from Hcy and inosine.
CATALYTIC ACTIVITY Reaction=H2O + S-inosyl-L-homocysteine = inosine + L-homocysteine; Xref=Rhea:RHEA:59828, ChEBI:CHEBI:15377, ChEBI:CHEBI:17596, ChEBI:CHEBI:57985, ChEBI:CHEBI:58199; EC=; PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:59829;
PATHWAYAmino-acid biosynthesis; S-adenosyl-L-methionine biosynthesis.
MISCELLANEOUSSAH is a product of SAM methyltransferases and is known to be a feedback inhibitor of these enzymes. As a result of this inhibition, organisms have evolved efficient enzymes to metabolize SAH via different pathways. The pathway found in methanogens differs from the canonical pathway, it uses the deamination of S-adenosyl-L- homocysteine to form S-inosyl-L-homocysteine for the regeneration of SAM from S-adenosyl-L-homocysteine.
FUNCTIONMay play a key role in the regulation of the intracellular concentration of adenosylhomocysteine.
CATALYTIC ACTIVITY Reaction=H2O + S-adenosyl-L-homocysteine = adenosine + L-homocysteine; Xref=Rhea:RHEA:21708, ChEBI:CHEBI:15377, ChEBI:CHEBI:16335, ChEBI:CHEBI:57856, ChEBI:CHEBI:58199; EC=;
PATHWAYAmino-acid biosynthesis; L-homocysteine biosynthesis; L- homocysteine from S-adenosyl-L-homocysteine: step 1/1.
end case
COFACTOR Name=NAD(+); Xref=ChEBI:CHEBI:57540; Note=Binds 1 NAD(+) per subunit.;
SIMILARITYBelongs to the adenosylhomocysteinase family.

Keywords [?]

Gene Ontology [?]

case <OCellular component:Methanobacteria> or <OC:Methanococci> or <OC:Methanomicrobia> or <OC:Methanopyri>
GO:0016802; Molecular function:trialkylsulfonium hydrolase activity
else; https://www.ebi.ac.uk/QuickGO/term/else
GO:0004013; Molecular function:adenosylhomocysteinase activity
end case
GO:0006730; Biological process:one-carbon metabolic process
GO:0005737; Cellular component:cytoplasm

Cross-references [?]

Pfam PF05221; AdoHcyase; 1;
Pfam PF00670; AdoHcyase_NAD; 1;
PIRSF PIRSF001109; Ad_hcy_hydrolase; 1;
NCBIfam TIGR00936; AhcY; 1;

Features [?]

From: SAHH_BURP1 (Q3JY79)
Key From To Description Tag Condition FTGroup
BINDING 200 202 /ligand="NAD(+)"
BINDING 263 268 /ligand="NAD(+)"
BINDING 342 344 /ligand="NAD(+)"
BINDING 64 64 /ligand="substrate" T
BINDING 139 139 /ligand="substrate" D
BINDING 199 199 /ligand="substrate" E
BINDING 229 229 /ligand="substrate" K
BINDING 233 233 /ligand="substrate" D
BINDING 234 234 /ligand="NAD(+)"
BINDING 286 286 /ligand="NAD(+)"
BINDING 321 321 /ligand="NAD(+)"
BINDING 387 387 /ligand="NAD(+)"

Additional information [?]

Size range 404-496 amino acids
Related rules None
Fusion Nter: None Cter: None

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