AC   MF_00563;
DC   Protein; auto
TR   HAMAP; MF_00563; -; 1; level=0
XX
Names: AdoHcyase
XX
case <OC:Methanobacteria> or <OC:Methanococci> or <OC:Methanomicrobia> or <OC:Methanopyri>
ID   SIHH
DE   RecName: Full=S-inosyl-L-homocysteine hydrolase;
DE            Short=SIHH;
DE            EC=3.13.1.9;
else
ID   SAHH
DE   RecName: Full=Adenosylhomocysteinase;
DE            EC=3.13.2.1;
DE   AltName: Full=S-adenosyl-L-homocysteine hydrolase;
DE            Short=AdoHcyase;
GN   Name=ahcY;
end case
XX
case <OC:Methanobacteria> or <OC:Methanococci> or <OC:Methanomicrobia> or <OC:Methanopyri>
CC   -!- FUNCTION: Catalyzes the hydrolysis of S-inosyl-L-homocysteine (SIH) to
CC       L-homocysteine (Hcy) and inosine. Likely functions in a S-adenosyl-L-
CC       methionine (SAM) recycling pathway from S-adenosyl-L-homocysteine (SAH)
CC       produced from SAM-dependent methylation reactions. Can also catalyze
CC       the reverse reaction in vitro, i.e. the synthesis of SIH from Hcy and
CC       inosine.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=H2O + S-inosyl-L-homocysteine = inosine + L-homocysteine;
CC         Xref=Rhea:RHEA:59828, ChEBI:CHEBI:15377, ChEBI:CHEBI:17596,
CC         ChEBI:CHEBI:57985, ChEBI:CHEBI:58199; EC=3.13.1.9;
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:59829;
CC   -!- PATHWAY: Amino-acid biosynthesis; S-adenosyl-L-methionine biosynthesis.
CC   -!- MISCELLANEOUS: SAH is a product of SAM methyltransferases and is known
CC       to be a feedback inhibitor of these enzymes. As a result of this
CC       inhibition, organisms have evolved efficient enzymes to metabolize SAH
CC       via different pathways. The pathway found in methanogens differs from
CC       the canonical pathway, it uses the deamination of S-adenosyl-L-
CC       homocysteine to form S-inosyl-L-homocysteine for the regeneration of
CC       SAM from S-adenosyl-L-homocysteine.
else
CC   -!- FUNCTION: May play a key role in the regulation of the intracellular
CC       concentration of adenosylhomocysteine.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=H2O + S-adenosyl-L-homocysteine = adenosine + L-homocysteine;
CC         Xref=Rhea:RHEA:21708, ChEBI:CHEBI:15377, ChEBI:CHEBI:16335,
CC         ChEBI:CHEBI:57856, ChEBI:CHEBI:58199; EC=3.13.2.1;
CC   -!- PATHWAY: Amino-acid biosynthesis; L-homocysteine biosynthesis; L-
CC       homocysteine from S-adenosyl-L-homocysteine: step 1/1.
end case
CC   -!- COFACTOR:
CC       Name=NAD(+); Xref=ChEBI:CHEBI:57540;
CC       Note=Binds 1 NAD(+) per subunit.;
CC   -!- SUBCELLULAR LOCATION: Cytoplasm.
CC   -!- SIMILARITY: Belongs to the adenosylhomocysteinase family.
XX
DR   Pfam; PF05221; AdoHcyase; 1; trigger=no
DR   Pfam; PF00670; AdoHcyase_NAD; 1; trigger=no
DR   PIRSF; PIRSF001109; Ad_hcy_hydrolase; 1; trigger=no
DR   NCBIfam; TIGR00936; AhcY; 1; trigger=no
DR   PROSITE; PS00738; ADOHCYASE_1; 1; trigger=no
DR   PROSITE; PS00739; ADOHCYASE_2; 1; trigger=no
XX
KW   Cytoplasm
KW   Hydrolase
KW   NAD
KW   One-carbon metabolism
XX
case <OC:Methanobacteria> or <OC:Methanococci> or <OC:Methanomicrobia> or <OC:Methanopyri>
GO   GO:0016802; F:trialkylsulfonium hydrolase activity
else
GO   GO:0004013; F:adenosylhomocysteinase activity
end case
GO   GO:0006730; P:one-carbon metabolic process
GO   GO:0005737; C:cytoplasm
XX
FT   From: SAHH_BURP1 (Q3JY79)
FT   BINDING         200..202
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT   Condition: T-T-[TA]
FT   BINDING         263..268
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT   Condition: G-[YF]-G-x-x-G
FT   BINDING         342..344
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT   Condition: [ISA]-G-H
FT   BINDING         64
FT                   /ligand="substrate"
FT   Optional; Condition: T
FT   BINDING         139
FT                   /ligand="substrate"
FT   Optional; Condition: D
FT   BINDING         199
FT                   /ligand="substrate"
FT   Optional; Condition: E
FT   BINDING         229
FT                   /ligand="substrate"
FT   Optional; Condition: K
FT   BINDING         233
FT                   /ligand="substrate"
FT   Optional; Condition: D
FT   BINDING         234
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT   Optional; Condition: N
FT   BINDING         286
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT   Optional; Condition: E
FT   BINDING         321
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT   Optional; Condition: N
FT   BINDING         387
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT   Optional; Condition: N
XX
Size: 404-496;
Related: None;
Template: P10760; P28183; Q58783; Q3JY79;
Scope:
 Bacteria
 Archaea
Fusion:
 Nter: None
 Cter: None
Duplicate: None
Plasmid: None
Comments: None
XX
# Revision 1.41 2023/06/01
//