ID   METB_HERAU              Reviewed;         319 AA.
AC   P24601;
DT   01-MAR-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-1992, sequence version 1.
DT   02-SEP-2026, entry version 101.
DE   RecName: Full=Probable cystathionine gamma-synthase;
DE            Short=CGS;
DE            EC=2.5.1.48;
DE   AltName: Full=O-succinylhomoserine (thiol)-lyase;
DE   Flags: Fragment;
GN   Name=metB;
OS   Herpetosiphon aurantiacus (Herpetosiphon giganteus).
OC   Bacteria; Bacillati; Chloroflexota; Chloroflexia; Herpetosiphonales;
OC   Herpetosiphonaceae; Herpetosiphon.
OX   NCBI_TaxID=65;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=HPA2;
RX   PubMed=2020544; DOI=10.1093/nar/19.5.1049;
RA   Duesterhoeft A., Erdmann D., Kroeger M.;
RT   "Stepwise cloning and molecular characterization of the HgiDI restriction-
RT   modification system from Herpetosiphon giganteus Hpa2.";
RL   Nucleic Acids Res. 19:1049-1056(1991).
CC   -!- FUNCTION: Catalyzes the formation of L-cystathionine from O-succinyl-L-
CC       homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In
CC       the absence of thiol, catalyzes gamma-elimination to form 2-
CC       oxobutanoate, succinate and ammonia (By similarity). {ECO:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=O-succinyl-L-homoserine + L-cysteine = L,L-cystathionine +
CC         succinate + H(+); Xref=Rhea:RHEA:20397, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:30031, ChEBI:CHEBI:35235, ChEBI:CHEBI:57661,
CC         ChEBI:CHEBI:58161; EC=2.5.1.48;
CC   -!- COFACTOR:
CC       Name=pyridoxal 5'-phosphate; Xref=ChEBI:CHEBI:597326;
CC         Evidence={ECO:0000250};
CC       Note=Binds 1 pyridoxal phosphate per subunit. {ECO:0000250};
CC   -!- SUBUNIT: Homotetramer. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the trans-sulfuration enzymes family.
CC       {ECO:0000305}.
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DR   EMBL; X55140; CAA38939.1; -; Genomic_DNA.
DR   PIR; S14030; S14030.
DR   AlphaFoldDB; P24601; -.
DR   SMR; P24601; -.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0004123; F:cystathionine gamma-lyase activity; IEA:TreeGrafter.
DR   GO; GO:0003962; F:cystathionine gamma-synthase activity; IEA:UniProtKB-EC.
DR   GO; GO:0030170; F:pyridoxal phosphate binding; IEA:InterPro.
DR   GO; GO:0019346; P:transsulfuration; IEA:InterPro.
DR   CDD; cd00614; CGS_like; 1.
DR   FunFam; 3.40.640.10:FF:000009; Cystathionine gamma-synthase homolog; 1.
DR   Gene3D; 3.90.1150.10; Aspartate Aminotransferase, domain 1; 1.
DR   Gene3D; 3.40.640.10; Type I PLP-dependent aspartate aminotransferase-like (Major domain); 1.
DR   InterPro; IPR000277; Cys/Met-Metab_PyrdxlP-dep_enz.
DR   InterPro; IPR054542; Cys_met_metab_PP.
DR   InterPro; IPR015424; PyrdxlP-dep_Trfase.
DR   InterPro; IPR015421; PyrdxlP-dep_Trfase_major.
DR   InterPro; IPR015422; PyrdxlP-dep_Trfase_small.
DR   PANTHER; PTHR11808:SF15; CYSTATHIONINE GAMMA-LYASE; 1.
DR   PANTHER; PTHR11808; TRANS-SULFURATION ENZYME FAMILY MEMBER; 1.
DR   Pfam; PF01053; Cys_Met_Meta_PP; 1.
DR   PIRSF; PIRSF001434; CGS; 1.
DR   SUPFAM; SSF53383; PLP-dependent transferases; 1.
DR   PROSITE; PS00868; CYS_MET_METAB_PP; 1.
PE   3: Inferred from homology;
KW   Amino-acid biosynthesis; Cytoplasm; Methionine biosynthesis;
KW   Pyridoxal phosphate; Transferase.
FT   CHAIN           1..>319
FT                   /note="Probable cystathionine gamma-synthase"
FT                   /id="PRO_0000114760"
FT   MOD_RES         197
FT                   /note="N6-(pyridoxal phosphate)lysine"
FT                   /evidence="ECO:0000250"
FT   NON_TER         319
SQ   SEQUENCE   319 AA;  34685 MW;  8C7D14992CC7BEBD CRC64;
     MDYGFATRAI HAGQDPESVT GAVIVPIYQT STYAQRGVGD HTGYEYSRTD NPTRTALQTC
     LAALEEAKHA LVFASGLGAS TTLMLMLKAG DHVICGDDVY GGTYRLFQRV MTEHGLSFDF
     IDMADPEAVR AAIKPNTRLI WLETPTNPLL KLAPIAAITR VAREHGIWTI VDNTFASPYN
     QRPITLGADM VLHSTTKYIG GHSDVVGGAI MTSNDELYEK LKFLQNAAGA VPGPFDCWLV
     LRGVKTLSIR MRDDERNALA IAQFLTEHPG VEKVIYPGLP SHPQHNLARE QMRGFGGMIS
     ILLKGGAEAA NAMVSKTKL
//