AC   MF_01262;
DC   Protein; auto
TR   HAMAP; MF_01262; -; 1; level=0
XX
Names: CCA_bact_type2
XX
ID   CCA
DE   RecName: Full=CCA-adding enzyme;
DE            EC=2.7.7.72;
DE   AltName: Full=CCA tRNA nucleotidyltransferase;
DE   AltName: Full=tRNA CCA-pyrophosphorylase;
DE   AltName: Full=tRNA adenylyl-/cytidylyl- transferase;
DE   AltName: Full=tRNA nucleotidyltransferase;
DE   AltName: Full=tRNA-NT;
GN   Name=cca;
XX
CC   -!- FUNCTION: Catalyzes the addition and repair of the essential 3'-
CC       terminal CCA sequence in tRNAs without using a nucleic acid template.
CC       Adds these three nucleotides in the order of C, C, and A to the tRNA
CC       nucleotide-73, using CTP and ATP as substrates and producing inorganic
CC       pyrophosphate. tRNA 3'-terminal CCA addition is required both for tRNA
CC       processing and repair. Also involved in tRNA surveillance by mediating
CC       tandem CCA addition to generate a CCACCA at the 3' terminus of unstable
CC       tRNAs. While stable tRNAs receive only 3'-terminal CCA, unstable tRNAs
CC       are marked with CCACCA and rapidly degraded.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=a tRNA precursor + ATP + 2 CTP = a tRNA with a 3' CCA end + 3
CC         diphosphate; Xref=Rhea:RHEA:14433, Rhea:RHEA-COMP:10465, Rhea:RHEA-
CC         COMP:10468, ChEBI:CHEBI:30616, ChEBI:CHEBI:33019, ChEBI:CHEBI:37563,
CC         ChEBI:CHEBI:74896, ChEBI:CHEBI:83071; EC=2.7.7.72;
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=a tRNA with a 3' CCA end + ATP + 2 CTP = a tRNA with a 3'
CC         CCACCA end + 3 diphosphate; Xref=Rhea:RHEA:76235, Rhea:RHEA-
CC         COMP:10468, Rhea:RHEA-COMP:18655, ChEBI:CHEBI:30616,
CC         ChEBI:CHEBI:33019, ChEBI:CHEBI:37563, ChEBI:CHEBI:83071,
CC         ChEBI:CHEBI:195187;
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:76236;
CC   -!- COFACTOR:
CC       Name=Mg(2+); Xref=ChEBI:CHEBI:18420;
CC   -!- MISCELLANEOUS: A single active site specifically recognizes both ATP
CC       and CTP and is responsible for their addition.
CC   -!- SIMILARITY: Belongs to the tRNA nucleotidyltransferase/poly(A)
CC       polymerase family. Bacterial CCA-adding enzyme type 2 subfamily.
XX
DR   Pfam; PF01743; PolyA_pol; 1; trigger=no
XX
KW   ATP-binding
KW   Magnesium
KW   Metal-binding
KW   Nucleotide-binding
KW   Nucleotidyltransferase
KW   RNA repair
KW   RNA-binding
KW   Transferase
KW   tRNA processing
XX
GO   GO:0000049; F:tRNA binding
GO   GO:0000166; F:nucleotide binding
GO   GO:0000287; F:magnesium ion binding
GO   GO:0004810; F:CCA tRNA nucleotidyltransferase activity
GO   GO:0005524; F:ATP binding
GO   GO:0001680; P:tRNA 3'-terminal CCA addition
XX
FT   From: CCA_BUCAI (P57169)
FT   BINDING         21
FT                   /ligand="Mg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:18420"
FT   Condition: [DE]
FT   BINDING         23
FT                   /ligand="Mg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:18420"
FT   Condition: D
FT   BINDING         8
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT   Condition: G
FT   BINDING         8
FT                   /ligand="CTP"
FT                   /ligand_id="ChEBI:CHEBI:37563"
FT   Condition: G
FT   BINDING         11
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT   Condition: R
FT   BINDING         11
FT                   /ligand="CTP"
FT                   /ligand_id="ChEBI:CHEBI:37563"
FT   Condition: R
FT   BINDING         91
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT   Condition: R
FT   BINDING         91
FT                   /ligand="CTP"
FT                   /ligand_id="ChEBI:CHEBI:37563"
FT   Condition: R
FT   BINDING         137
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT   Condition: R
FT   BINDING         137
FT                   /ligand="CTP"
FT                   /ligand_id="ChEBI:CHEBI:37563"
FT   Condition: R
FT   BINDING         140
FT                   /ligand="ATP"
FT                   /ligand_id="ChEBI:CHEBI:30616"
FT   Condition: R
FT   BINDING         140
FT                   /ligand="CTP"
FT                   /ligand_id="ChEBI:CHEBI:37563"
FT   Condition: R
XX
Size: 360-419;
Related: MF_01261!;
Template: P06961; Q7SIB1;
Scope:
 Bacteria; Pseudomonadota
Fusion:
 Nter: None
 Cter: None
Duplicate: None
Plasmid: None
Comments: The CCA-adding enzyme family consists of 4 different subfamilies:
 3 bacterial subfamilies (MF_01261, MF_01262 and MF_01263) and 1 archaeal
 subfamily (MF_01264).
 There is no characterized protein in this subfamily. The closest
 sequence homologs are from type 1 subfamily (MF_01261), which is also a
 proteobacterial family (E.coli is characterized) but which contains an HD
 domain associated with phosphohydrolase activities. As the type 2 subfamily
 does not contain such a domain, it should not possess phosphohydrolase activities.
 FT lines are propagated from G.stearothermophilus CCA-adding enzyme (type 3
 subfamily, MF_01263) whose X-ray structure is known.
XX
# Revision 1.19 2023/05/17
//