SIHH_METAC
ID SIHH_METAC Reviewed; 411 AA.
AC Q8TRA5;
DT 25-MAR-2003, integrated into UniProtKB/Swiss-Prot.
DT 01-JUN-2002, sequence version 1.
DT 03-AUG-2022, entry version 120.
DE RecName: Full=S-inosyl-L-homocysteine hydrolase {ECO:0000255|HAMAP-Rule:MF_00563};
DE Short=SIHH {ECO:0000255|HAMAP-Rule:MF_00563};
DE EC=3.13.1.9 {ECO:0000255|HAMAP-Rule:MF_00563};
GN Name=ahcY2 {ECO:0000312|EMBL:AAM04694.1}; OrderedLocusNames=MA_1275;
OS Methanosarcina acetivorans (strain ATCC 35395 / DSM 2834 / JCM 12185 /
OS C2A).
OC Archaea; Euryarchaeota; Stenosarchaea group; Methanomicrobia;
OC Methanosarcinales; Methanosarcinaceae; Methanosarcina.
OX NCBI_TaxID=188937;
RN [1]
RP NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC STRAIN=ATCC 35395 / DSM 2834 / JCM 12185 / C2A;
RX PubMed=11932238; DOI=10.1101/gr.223902;
RA Galagan J.E., Nusbaum C., Roy A., Endrizzi M.G., Macdonald P., FitzHugh W.,
RA Calvo S., Engels R., Smirnov S., Atnoor D., Brown A., Allen N., Naylor J.,
RA Stange-Thomann N., DeArellano K., Johnson R., Linton L., McEwan P.,
RA McKernan K., Talamas J., Tirrell A., Ye W., Zimmer A., Barber R.D.,
RA Cann I., Graham D.E., Grahame D.A., Guss A.M., Hedderich R.,
RA Ingram-Smith C., Kuettner H.C., Krzycki J.A., Leigh J.A., Li W., Liu J.,
RA Mukhopadhyay B., Reeve J.N., Smith K., Springer T.A., Umayam L.A.,
RA White O., White R.H., de Macario E.C., Ferry J.G., Jarrell K.F., Jing H.,
RA Macario A.J.L., Paulsen I.T., Pritchett M., Sowers K.R., Swanson R.V.,
RA Zinder S.H., Lander E., Metcalf W.W., Birren B.;
RT "The genome of Methanosarcina acetivorans reveals extensive metabolic and
RT physiological diversity.";
RL Genome Res. 12:532-542(2002).
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. {ECO:0000255|HAMAP-Rule:MF_00563}.
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 Evidence={ECO:0000255|HAMAP-Rule:MF_00563};
CC PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:59829;
CC Evidence={ECO:0000255|HAMAP-Rule:MF_00563};
CC -!- COFACTOR:
CC Name=NAD(+); Xref=ChEBI:CHEBI:57540;
CC Evidence={ECO:0000255|HAMAP-Rule:MF_00563};
CC Note=Binds 1 NAD(+) per subunit. {ECO:0000255|HAMAP-Rule:MF_00563};
CC -!- PATHWAY: Amino-acid biosynthesis; S-adenosyl-L-methionine biosynthesis.
CC {ECO:0000255|HAMAP-Rule:MF_00563}.
CC -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000255|HAMAP-Rule:MF_00563}.
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. {ECO:0000255|HAMAP-Rule:MF_00563}.
CC -!- SIMILARITY: Belongs to the adenosylhomocysteinase family.
CC {ECO:0000255|HAMAP-Rule:MF_00563}.
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DR EMBL; AE010299; AAM04694.1; -; Genomic_DNA.
DR RefSeq; WP_011021296.1; NC_003552.1.
DR AlphaFoldDB; Q8TRA5; -.
DR SMR; Q8TRA5; -.
DR STRING; 188937.MA_1275; -.
DR EnsemblBacteria; AAM04694; AAM04694; MA_1275.
DR GeneID; 1473163; -.
DR KEGG; mac:MA_1275; -.
DR HOGENOM; CLU_025194_2_1_2; -.
DR InParanoid; Q8TRA5; -.
DR OMA; NKYGCRE; -.
DR OrthoDB; 17629at2157; -.
DR PhylomeDB; Q8TRA5; -.
DR UniPathway; UPA00315; -.
DR Proteomes; UP000002487; Chromosome.
DR GO; GO:0005829; C:cytosol; IBA:GO_Central.
DR GO; GO:0004013; F:adenosylhomocysteinase activity; IBA:GO_Central.
DR GO; GO:0006730; P:one-carbon metabolic process; IEA:UniProtKB-UniRule.
DR GO; GO:0006556; P:S-adenosylmethionine biosynthetic process; IEA:UniProtKB-UniPathway.
DR GO; GO:0033353; P:S-adenosylmethionine cycle; IBA:GO_Central.
DR CDD; cd00401; SAHH; 1.
DR Gene3D; 3.40.50.1480; -; 1.
DR HAMAP; MF_00563; AdoHcyase; 1.
DR InterPro; IPR042172; Adenosylhomocyst_ase-like_sf.
DR InterPro; IPR000043; Adenosylhomocysteinase-like.
DR InterPro; IPR015878; Ado_hCys_hydrolase_NAD-bd.
DR InterPro; IPR036291; NAD(P)-bd_dom_sf.
DR InterPro; IPR020082; S-Ado-L-homoCys_hydrolase_CS.
DR PANTHER; PTHR23420; PTHR23420; 1.
DR Pfam; PF05221; AdoHcyase; 2.
DR Pfam; PF00670; AdoHcyase_NAD; 1.
DR PIRSF; PIRSF001109; Ad_hcy_hydrolase; 1.
DR SMART; SM00996; AdoHcyase; 1.
DR SMART; SM00997; AdoHcyase_NAD; 1.
DR SUPFAM; SSF51735; SSF51735; 1.
DR TIGRFAMs; TIGR00936; ahcY; 1.
DR PROSITE; PS00738; ADOHCYASE_1; 1.
DR PROSITE; PS00739; ADOHCYASE_2; 1.
PE 3: Inferred from homology;
KW Cytoplasm; Hydrolase; NAD; One-carbon metabolism; Reference proteome.
FT CHAIN 1..411
FT /note="S-inosyl-L-homocysteine hydrolase"
FT /id="PRO_0000117003"
FT BINDING 121
FT /ligand="substrate"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 146
FT /ligand="substrate"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 147..149
FT /ligand="NAD(+)"
FT /ligand_id="ChEBI:CHEBI:57540"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 176
FT /ligand="substrate"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 180
FT /ligand="substrate"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 181
FT /ligand="NAD(+)"
FT /ligand_id="ChEBI:CHEBI:57540"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 210..215
FT /ligand="NAD(+)"
FT /ligand_id="ChEBI:CHEBI:57540"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 233
FT /ligand="NAD(+)"
FT /ligand_id="ChEBI:CHEBI:57540"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 268
FT /ligand="NAD(+)"
FT /ligand_id="ChEBI:CHEBI:57540"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 289..291
FT /ligand="NAD(+)"
FT /ligand_id="ChEBI:CHEBI:57540"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
FT BINDING 335
FT /ligand="NAD(+)"
FT /ligand_id="ChEBI:CHEBI:57540"
FT /evidence="ECO:0000255|HAMAP-Rule:MF_00563"
SQ SEQUENCE 411 AA; 44900 MW; C3221440430631F2 CRC64;
MTEQELVESG NMKMEWARNH MPVIAIIREK FEKEKPLKGL KVGMALHVEA KTAVLVETLA
AGGAQVAISG CNPLSTQDDV ARALDTRKNI SCFARYGCCT SEYYEAIDKV LDIEPDITID
DGADLIFKLH KERTDLLPKI LGGCEETTTG VHRLHAMEKE GALKMPVIAV NDAMTKYLFD
NRYGTGQSAW DGINRTTNLL VAGKNVVVGG YGWCGRGVAM RAAGLGANVI VTEVDPIRAL
EARMDGYRVM RMADAARLGE IFVTTTGNRD ILTAEHFKVM PDGAVLANSG HFNVEIDMEA
LTSLAKSVKT VRHNIKEYDI GDRRINVIAE GRLVNLAAGD GHPAEVMDMS FANQALCVRY
IAENTLLNGV HGVPRGIDTY VAKLKLESMG ISIDELTSKQ ECYMTGWECG T
