HAMAP

Accession	MF_01262
Dates	29-JUL-2005 (Created) 28-JAN-2011 (Last updated, Version 8)

Data class

Protein

Predictors

HAMAP; MF_01262; [distribution of match scores in UniProtKB];[seed alignment for MF_01262]

Names

CCA_bact_type2

Identifier

CCA

Protein name

RecName: Full=CCA-adding enzyme; EC=2.7.7.72; AltName: Full=CCA tRNA nucleotidyltransferase; AltName: Full=tRNA CCA-pyrophosphorylase; AltName: Full=tRNA adenylyl-/cytidylyl- transferase; AltName: Full=tRNA nucleotidyltransferase; AltName: Full=tRNA-NT;

Gene name

cca

FUNCTION: Catalyzes the addition and repair of the essential 3'-terminal CCA sequence in tRNAs without using a nucleic acid template. Adds these three nucleotides in the order of C, C, and A to the tRNA nucleotide-73, using CTP and ATP as substrates and producing inorganic pyrophosphate (By similarity).

CATALYTIC ACTIVITY: A tRNA precursor + 2 CTP + ATP = a tRNA with a 3' CCA end + 3 diphosphate.

COFACTOR: Magnesium (By similarity).

MISCELLANEOUS: A single active site specifically recognizes both ATP and CTP and is responsible for their addition (By similarity).

SIMILARITY: Belongs to the tRNA nucleotidyltransferase/poly(A) polymerase family. Bacterial CCA-adding enzyme type 2 subfamily.

Pfam	PF01743; PolyA_pol; 1;

ATP-binding, Magnesium, Metal-binding, Nucleotide-binding, Nucleotidyltransferase, RNA repair, RNA-binding, Transferase, tRNA processing.

GO:0000049; Molecular function: tRNA binding.
GO:0000166; Molecular function: nucleotide binding.
GO:0000287; Molecular function: magnesium ion binding.
GO:0004810; Molecular function: tRNA adenylyltransferase activity.
GO:0005524; Molecular function: ATP binding.
GO:0016437; Molecular function: tRNA cytidylyltransferase activity.
GO:0001680; Biological process: tRNA 3'-terminal CCA addition.

From: CCA_BUCAI (P57169)
Key		From		To		Description		Condition		FTGroup
METAL		21		21		Magnesium (By similarity)		[DE]
METAL		23		23		Magnesium (By similarity)		D
BINDING		8		8		ATP or CTP; via amide nitrogen (By similarity)		G
BINDING		11		11		ATP or CTP (By similarity)		R
BINDING		91		91		ATP or CTP (By similarity)		R
BINDING		137		137		ATP or CTP (By similarity)		R
BINDING		140		140		ATP or CTP (By similarity)		R

Size range:	360-419 amino acids
Related UniRules:	MF_01261 (CCA (supersedes the current rule))
Template:	P06961 (CCA_ECOLI); Q7SIB1 (CCA_GEOSE): [Recover all]
Scope:	Bacteria; Proteobacteria
Fusion:	Nter: None; Cter: None
Duplicate:	None
Plasmid encoded:	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 B.stearothermophilus CCA-adding enzyme (type 3 subfamily, MF_01263) whose X-ray structure is known.