AC   MF_01963;
DC   Protein; auto
c?   <OC:Bacteria> or <OC:Archaea>
TR   HAMAP; MF_01963; -; 1; level=0
XX
Names: MTAP
XX
case <FT:3=D-x-D> and <FT:7=S> and <FT:8=[AVMI]>
ID   MTAP
DE   RecName: Full=S-methyl-5'-thioadenosine phosphorylase;
DE            EC=2.4.2.28;
DE   AltName: Full=5'-methylthioadenosine phosphorylase;
DE            Short=MTA phosphorylase;
DE            Short=MTAP;
GN   Name=mtnP;
else case <FT:3=N-x-A> and <FT:7=E> and <FT:8=[AVMI]>
ID   MTIP
DE   RecName: Full=Probable S-methyl-5'-thioinosine phosphorylase;
DE            EC=2.4.2.44;
DE   AltName: Full=5'-methylthioinosine phosphorylase;
DE            Short=MTI phosphorylase;
DE            Short=MTIP;
else case <FT:3=N-x-A> and <FT:7=E> and not <FT:8=[AVMI]>
ID   PNPH
DE   RecName: Full=Probable 6-oxopurine nucleoside phosphorylase;
DE            EC=2.4.2.1;
DE   AltName: Full=Purine nucleoside phosphorylase;
DE            Short=PNP;
else
ID   PNPH
DE   RecName: Full=Purine nucleoside phosphorylase;
DE            Short=PNP;
DE            EC=2.4.2.1;
end case
XX
case <FT:3=D-x-D> and <FT:7=S> and <FT:8=[AVMI]>
CC   -!- FUNCTION: Catalyzes the reversible phosphorylation of S-methyl-5'-
CC       thioadenosine (MTA) to adenine and 5-methylthioribose-1-phosphate.
CC       Involved in the breakdown of MTA, a major by-product of polyamine
CC       biosynthesis. Responsible for the first step in the methionine salvage
CC       pathway after MTA has been generated from S-adenosylmethionine. Has
CC       broad substrate specificity with 6-aminopurine nucleosides as preferred
CC       substrates.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=phosphate + S-methyl-5'-thioadenosine = adenine + S-methyl-5-
CC         thio-alpha-D-ribose 1-phosphate; Xref=Rhea:RHEA:11852,
CC         ChEBI:CHEBI:16708, ChEBI:CHEBI:17509, ChEBI:CHEBI:43474,
CC         ChEBI:CHEBI:58533; EC=2.4.2.28;
CC   -!- PATHWAY: Amino-acid biosynthesis; L-methionine biosynthesis via salvage
CC       pathway; S-methyl-5-thio-alpha-D-ribose 1-phosphate from S-methyl-5'-
CC       thioadenosine (phosphorylase route): step 1/1.
CC   -!- SUBUNIT: Homohexamer. Dimer of a homotrimer.
else case <FT:3=N-x-A> and <FT:7=E> and <FT:8=[AVMI]>
CC   -!- FUNCTION: Catalyzes the reversible phosphorylation of S-methyl-5'-
CC       thioinosine (MTI) to hypoxanthine and 5-methylthioribose-1-phosphate.
CC       Involved in the breakdown of S-methyl-5'-thioadenosine (MTA), a major
CC       by-product of polyamine biosynthesis. Catabolism of (MTA) occurs via
CC       deamination to MTI and phosphorolysis to hypoxanthine.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=phosphate + S-methyl-5'-thioinosine = hypoxanthine + S-methyl-
CC         5-thio-alpha-D-ribose 1-phosphate; Xref=Rhea:RHEA:30643,
CC         ChEBI:CHEBI:17368, ChEBI:CHEBI:43474, ChEBI:CHEBI:48595,
CC         ChEBI:CHEBI:58533; EC=2.4.2.44;
CC   -!- PATHWAY: Purine metabolism; purine nucleoside salvage.
CC   -!- SUBUNIT: Homotrimer.
CC   -!- MISCELLANEOUS: Although this enzyme belongs to the family of MTA
CC       phosphorylases based on sequence homology, it has been shown that
CC       conserved amino acid substitutions in the substrate binding pocket
CC       convert the substrate specificity of this enzyme from 6-aminopurines to
CC       6-oxopurines.
else case <FT:3=N-x-A> and <FT:7=E>
CC   -!- FUNCTION: Purine nucleoside phosphorylase which is highly specific for
CC       6-oxopurine nucleosides. Cleaves guanosine or inosine to respective
CC       bases and sugar-1-phosphate molecules. Involved in purine salvage.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=a purine D-ribonucleoside + phosphate = a purine nucleobase +
CC         alpha-D-ribose 1-phosphate; Xref=Rhea:RHEA:19805, ChEBI:CHEBI:26386,
CC         ChEBI:CHEBI:43474, ChEBI:CHEBI:57720, ChEBI:CHEBI:142355; EC=2.4.2.1;
CC   -!- PATHWAY: Purine metabolism; purine nucleoside salvage.
CC   -!- SUBUNIT: Homohexamer. Dimer of a homotrimer.
CC   -!- MISCELLANEOUS: Although this enzyme belongs to the family of MTA
CC       phosphorylases based on sequence homology, it has been shown that
CC       conserved amino acid substitutions in the substrate binding pocket
CC       convert the substrate specificity of this enzyme from 6-aminopurines to
CC       6-oxopurines.
else
CC   -!- FUNCTION: Purine nucleoside phosphorylase involved in purine salvage.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=a purine D-ribonucleoside + phosphate = a purine nucleobase +
CC         alpha-D-ribose 1-phosphate; Xref=Rhea:RHEA:19805, ChEBI:CHEBI:26386,
CC         ChEBI:CHEBI:43474, ChEBI:CHEBI:57720, ChEBI:CHEBI:142355; EC=2.4.2.1;
CC   -!- PATHWAY: Purine metabolism; purine nucleoside salvage.
CC   -!- SUBUNIT: Homohexamer. Dimer of a homotrimer.
CC   -!- MISCELLANEOUS: Although this enzyme belongs to the family of MTA
CC       phosphorylases based on sequence homology, it lacks several conserved
CC       amino acids in the substrate binding pocket that confer specificity
CC       towards MTA.
end case
CC   -!- SIMILARITY: Belongs to the PNP/MTAP phosphorylase family. MTAP
CC       subfamily.
XX
DR   PROSITE; PS01240; PNP_MTAP_2; 1; trigger=no
DR   Pfam; PF01048; PNP_UDP_1; 1; trigger=no
DR   NCBIfam; TIGR01694; MTAP; 1; trigger=no
XX
KW   Glycosyltransferase
KW   Purine salvage
KW   Transferase
XX
case <FT:3=D-x-D> and <FT:7=S> and <FT:8=[AVI]>
GO   GO:0017061; F:S-methyl-5-thioadenosine phosphorylase activity
GO   GO:0019509; P:L-methionine salvage from methylthioadenosine
else
GO   GO:0016763; F:pentosyltransferase activity
GO   GO:0006166; P:purine ribonucleoside salvage
end case
XX
FT   From: MTAP_SACS2 (Q97W94)
FT   BINDING         58..59
FT                   /ligand="phosphate"
FT                   /ligand_id="ChEBI:CHEBI:43474"
FT   Condition: R-[HN]
FT   BINDING         91..92
FT                   /ligand="phosphate"
FT                   /ligand_id="ChEBI:CHEBI:43474"
FT   Optional; Condition: [ST]-A
FT   BINDING         214..216
FT                   /ligand="substrate"
FT   Condition: [DN]-x-[DA]
FT   BINDING         16
FT                   /ligand="phosphate"
FT                   /ligand_id="ChEBI:CHEBI:43474"
FT   Condition: [ST]
FT   BINDING         190
FT                   /ligand="substrate"
FT   Condition: M
FT   BINDING         191
FT                   /ligand="phosphate"
FT                   /ligand_id="ChEBI:CHEBI:43474"
FT   Condition: [ST]
FT   From: PNPH_PYRFU (Q8U2I1)
FT   SITE            169
FT                   /note="Important for substrate specificity"
FT   Condition: [SE]
FT   SITE            223
FT                   /note="Important for substrate specificity"
XX
Size: 237-355;
Related: None;
Template: Q97W94; Q8U4Q8; Q8U2I1; Q9HZK1;
Scope:
 Bacteria
 Archaea
Fusion:
 Nter: None
 Cter: None
Duplicate: in PYRFU, THEKO
Plasmid: None
Comments: None
XX
# Revision 1.18 2023/06/01
//