>TIGR00392 ileS isoleucyl-tRNA synthetase; InterPro: IPR002301 The aminoacyl-tRNA synthetases (6.1.1. from EC) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have limited sequence homology . The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossman fold catalytic domain and are mostly monomeric . Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices , and are mostly dimeric or multimeric, containing at least three conserved regions , , . However, tRNA binding involves an alpha-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan and valine belong to class I synthetases; these synthetases are further divided into three subclasses, a, b and c, according to sequence homology. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, phenylalanine, proline, serine, and threonine belong to class-II synthetases . Isoleucyl-tRNA synthetase (6.1.1.5 from EC) is an alpha monomer that belongs to class Ia. The enzyme, isoleucyl-transfer RNA synthetase, activates not only the cognate substrate L-isoleucine but also the minimally distinct L-valine in the first, aminoacylation step. Then, in a second, "editing" step, the synthetase itself rapidly hydrolyzes only the valylated products , as shown from the crystal structures. ; GO: 0000166 nucleotide binding, 0004822 isoleucine-tRNA ligase activity, 0005524 ATP binding, 0006412 translation, 0006428 isoleucyl-tRNA aminoacylation, 0005737 cytoplasm.

Probab=96.06  E-value=0.044  Score=35.26  Aligned_cols=115  Identities=17%  Similarity=0.213  Sum_probs=88.1

Q ss_pred             CCCCCCCCCCCCHHHHHHHHHHHHHHHHCCCCCEEEEEC--------------------CCCCCHHH-HHHHHHCCCCCC
Q ss_conf             788884441112799999999999997079984579960--------------------55233888-999987089864
Q gi|254780573|r   33 PTVYDFAHIGNARPMIVFDVLYRLLRYYYGEKCVTYVRN--------------------ITDIDDKI-IERARQEHPSIP   91 (461)
Q Consensus        33 pTvy~~~HiG~~r~~v~~D~l~R~L~~~~~~~~V~~v~n--------------------iTDidDki-i~~a~~~~~~~~   91 (461)
T Consensus        45 PYAnG~iHlGHalNKilKDii~Ryk~m~G~~--v~~~pGWDtHGLPIE~~Vek~lg~~~~~~~~~~~g~E~fr-------  115 (938)
T TIGR00392        45 PYANGAIHLGHALNKILKDIILRYKTMQGYN--VTYKPGWDTHGLPIELKVEKKLGISGKKEIESLEGIEEFR-------  115 (938)
T ss_pred             CCCCCCCCHHHHHHHHHHHHHHHHCCCCCEE--CCCCCCCCCCCCCEEEEEECCCCCCCCCCCCHHHHHHHHH-------
T ss_conf             8767997402556667611232101122500--3204786657870244564047876400022044389999-------


Q ss_pred             CCCCHHHHHHHHHHHHHHHHHHHCCCCCCH---HHHHHHHHHHHHHHHHHHHHCCCCCCCCCCEEECCHH
Q ss_conf             488489999999999999877626854100---0123567777899999874114320128928752200
Q gi|254780573|r   92 INDAISIITSKNTQQFVKDTTRLACLAPTH---QPRATNHIPQMIYLIQNIILHGHAYEANNEIIFDTSS  158 (461)
Q Consensus        92 ~~~~~~~~a~~~~~~f~~d~~~L~v~~p~~---~pr~t~~i~~~i~~i~~L~~~g~aY~~~g~VyFdv~~  158 (461)
T Consensus       116 --~~Cr~~A~~~~~~q~~~F~rLG~w~Dwe~pY~T~d~~y~~~~w~~l~~~~eKGL~~~~~kpv~WSp~~  183 (938)
T TIGR00392       116 --EKCREFALKQIEEQREQFQRLGVWGDWENPYKTMDPSYEESQWWLLKELHEKGLLYRGLKPVYWSPRC  183 (938)
T ss_pred             --HHHHHHHHHHHHHHHHHHHHCEEECCCCCCCCCCCHHHHHHHHHHHHHHHHCCCEEECCEEECCCCCC
T ss_conf             --99999999999999988885312022557850678899999999999997524202255221144144