HMM Summary Page: TIGR00442

Functionhistidine--tRNA ligase
Gene SymbolhisS
Trusted Cutoff286.75
Domain Trusted Cutoff286.75
Noise Cutoff246.90
Domain Noise Cutoff246.90
Isology Typeequivalog
EC Number6.1.1.21
HMM Length406
Mainrole CategoryProtein synthesis
Subrole CategorytRNA aminoacylation
Gene Ontology TermGO:0004821: histidine-tRNA ligase activity molecular_function
GO:0005737: cytoplasm cellular_component
GO:0006427: histidyl-tRNA aminoacylation biological_process
AuthorHaft DH
Entry DateApr 20 1999 2:08PM
Last ModifiedFeb 14 2011 3:27PM
CommentThis model finds a histidyl-tRNA synthetase in every completed genome. Apparent second copies from Bacillus subtilis, Synechocystis sp., and Aquifex aeolicus are slightly shorter, more closely related to each other than to other hisS proteins, and actually serve as regulatory subunits for an enzyme of histidine biosynthesis. They were excluded from the seed alignment and score much lower than do single copy histidyl-tRNA synthetases of other genomes not included in the seed alignment. These putative second copies of HisS score below the trusted cutoff. The regulatory protein kinase GCN2 of Saccharomyces cerevisiae (YDR283c), and related proteins from other species designated eIF-2 alpha kinase, have a domain closely related to histidyl-tRNA synthetase that may serve to detect and respond to uncharged tRNA(his), an indicator of amino acid starvation; these regulatory proteins are not orthologous and so score below the noise cutoff.
ReferencesDR HAMAP; MF_00127; 475 of 485
Genome PropertyGenProp0258: tRNA aminoacylation (HMM)
GenProp0799: bacterial core gene set, exactly 1 per genome (HMM)