HAMAP

Accession	MF_02003
Dates	5-DEC-2005 (Created) 21-NOV-2011 (Last updated, Version 15)

Data class

Protein

Predictors

HAMAP; MF_02003; [distribution of match scores in UniProtKB];[seed alignment for MF_02003]

Names

Ile_tRNA_synth_type2

Identifier

SYI

Protein name

RecName: Full=Isoleucine--tRNA ligase; EC=6.1.1.5; AltName: Full=Isoleucyl-tRNA synthetase; Short=IleRS;

Gene name

ileS

FUNCTION: Catalyzes the attachment of isoleucine to tRNA(Ile). As IleRS can inadvertently accommodate and process structurally similar amino acids such as valine, to avoid such errors it has two additional distinct tRNA(Ile)-dependent editing activities. One activity is designated as 'pretransfer' editing and involves the hydrolysis of activated Val-AMP. The other activity is designated 'posttransfer' editing and involves deacylation of mischarged Val-tRNA(Ile) (By similarity).

CATALYTIC ACTIVITY: ATP + L-isoleucine + tRNA(Ile) = AMP + diphosphate + L-isoleucyl-tRNA(Ile).

COFACTOR: Zinc (By similarity).

SUBUNIT: Monomer (By similarity).

SUBCELLULAR LOCATION: Cytoplasm (By similarity).

DOMAIN: IleRS has two distinct active sites: one for aminoacylation and one for editing. The misactivated valine is translocated from the active site to the editing site, which sterically excludes the correctly activated isoleucine. The single editing site contains two valyl binding pockets, one specific for each substrate (Val-AMP or Val-tRNA(Ile)) (By similarity).

SIMILARITY: Belongs to the class-I aminoacyl-tRNA synthetase family. IleS type 2 subfamily.

PROSITE	PS00178; AA_TRNA_LIGASE_I; 1;
Pfam	PF00133; tRNA-synt_1; 1;
PRINTS	PR00984; TRNASYNTHILE; 1;
TIGRFAMs	TIGR00392; IleS; 1;

Cytoplasm, Aminoacyl-tRNA synthetase, ATP-binding, Ligase, Nucleotide-binding, Protein biosynthesis, Metal-binding, Zinc.

GO:0004822; Molecular function: isoleucine-tRNA ligase activity.
GO:0005524; Molecular function: ATP binding.
GO:0008270; Molecular function: zinc ion binding.
GO:0006428; Biological process: isoleucyl-tRNA aminoacylation.
GO:0005737; Cellular component: cytoplasm.

From: SYI_THET8 (P56690)
Key		From		To		Description		Condition		FTGroup
MOTIF		47		57		"HIGH" region
MOTIF		591		595		"KMSKS" region
BINDING		594		594		ATP (By similarity)		K

Size range:	981-1213 amino acids
Related UniRules:	MF_02002 (SYI)
Template:	P56690 (SYI_THET8); P00956 (SYI_ECOLI); P41368 (SYI2_STAAU); Q10765 (SYI_MYCTU); Q8L1B1 (SYI2_PSEFL): [Recover all]
Scope:	Bacteria Archaea
Fusion:	Nter: None; Cter: None
Duplicate:	None
Plasmid encoded:	in STAAU
Comments:	Some species have a second copy of IleRS in another subfamily (MF_02002). MYCTU, PSEFL and STAAU confer high-level resistance to the antibiotic mupirocin (pseudomonic acid A), an Ile-analog that competitively inhibits activation by Ile-tRNA synthetase, thus inhibiting protein biosynthesis. Shorter N-terminal in SULSO; sequence not included in alignment and not taken into account in size range.