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Annotation rule MF_00563
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General rule information [?]

Accession MF_00563
Dates 4-JUN-2002 (Created)
4-SEP-2020 (Last updated, Version 37)
Name AdoHcyase
Scope
Bacteria
Archaea
Templates P10760 (SAHH_RAT); P28183 (SAHH_RHOCB); Q58783 (SIHH_METJA); Q3JY79 (SAHH_BURP1): [Recover all]

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;
Short=SIHH;
EC 3.13.1.9;
else
Identifier
SAHH
Protein name
RecName: Full=Adenosylhomocysteinase;
EC 3.3.1.1;
AltName: Full=S-adenosyl-L-homocysteine hydrolase;
Short=AdoHcyase;
Gene name
ahcY
end case

Comments [?]

case <OC:Methanobacteria> or <OC:Methanococci> or <OC:Methanomicrobia> or <OC:Methanopyri>
Function Catalyzes 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 RHEA:59828: H2O + S-inosyl-L-homocysteine = inosine + L-homocysteine
EC 3.13.1.9
PhysiologicalDirection=left-to-right (RHEA:59829)
Pathway Amino-acid biosynthesis; S-adenosyl-L-methionine biosynthesis.
Miscellaneous SAH 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.
else
Function May play a key role in the regulation of the intracellular concentration of adenosylhomocysteine.
Catalytic activity RHEA:21708: H2O + S-adenosyl-L-homocysteine = adenosine + L-homocysteine
EC 3.3.1.1
Pathway Amino-acid biosynthesis; L-homocysteine biosynthesis; L-homocysteine from S-adenosyl-L-homocysteine: step 1/1.
end case
Cofactor NAD(+)
Note: Binds 1 NAD(+) per subunit.
Subcellular location Cytoplasm.
Similarity Belongs to the adenosylhomocysteinase family.

Keywords [?]


Gene Ontology [?]

case <OC:Methanobacteria> or <OC:Methanococci> or <OC:Methanomicrobia> or <OC:Methanopyri>
GO:0016802; Molecular function: trialkylsulfonium hydrolase activity.
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;
PF00670; AdoHcyase_NAD; 1;
PIRSF PIRSF001109; Ad_hcy_hydrolase; 1;
TIGRFAMs TIGR00936; AhcY; 1;
PROSITE PS00738; ADOHCYASE_1; 1;
PS00739; ADOHCYASE_2; 1;

Features [?]

From: SAHH_BURP1 (Q3JY79)
Key     From     To       Description   Tag   Condition   FTGroup
NP_BIND     200     202       NAD     T-T-[TA]  
NP_BIND     263     268       NAD     G-[YF]-G-x-x-G  
NP_BIND     342     344       NAD     [ISA]-G-H  
BINDING (Optional)     64     64       Substrate     T  
BINDING (Optional)     139     139       Substrate     D  
BINDING (Optional)     199     199       Substrate     E  
BINDING (Optional)     229     229       Substrate     K  
BINDING (Optional)     233     233       Substrate     D  
BINDING (Optional)     234     234       NAD     N  
BINDING (Optional)     286     286       NAD     E  
BINDING (Optional)     321     321       NAD     N  
BINDING (Optional)     387     387       NAD     N  

Additional information [?]

Size range 404-496 amino acids
Related rules None
Fusion None