>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=99.33  E-value=3.2e-12  Score=107.70  Aligned_cols=123  Identities=22%  Similarity=0.241  Sum_probs=86.7

Q ss_pred             HHHHC--CCCCCHHHEECCCEEEEEECCCCCCCCCCCCHHHHHC-CCCCCCCCCCHHHHHHHHHCC--CCCCCCCCCHHH
Q ss_conf             88640--8753012100343257642022332332140899850-253345577799999998425--664321145034
Q gi|254780573|r  252 SCCAD--RIEKTANIWIHNGFLNLEGRKMSKSNGNFITINELLE-TKKFGGRSWPAPVIRLAMLMT--HYREPIDFTVQR  326 (461)
Q Consensus       252 s~a~~--~~~~~a~yWlH~G~l~i~geKMSKSlGN~iti~dlL~-~~~~~~k~y~p~viR~~lLss--hYRspLdfS~e~  326 (461)
T Consensus       642 ~~~~~nv~~~PYK~Vi~hGF~LDe~G~KMSKSlGNvV~P~~v~~G~~N~~~P~yGAD~LRlyv~~~P~~~~~Dl~~~~~~  721 (938)
T TIGR00392       642 GVALFNVGKAPYKNVITHGFTLDEKGRKMSKSLGNVVDPEKVINGDENLKLPKYGADILRLYVASSPSDYWEDLRFSDEI  721 (938)
T ss_pred             HHHHHCCCCCCCCEEEECCEEECCCCCCCCCCCCCCCCHHHHCCCCCCCCCCCCCCHHHHHHHHHCCCCCHHCCCCCHHH
T ss_conf             99987078854363453154885778544532587038599708843358875330487777884687400022006689


Q ss_pred             HHHHHHHHHHCCC----CCC---CCCC---------------CCHHHHH----------HCCCHHHHHHHHHHHHHHHHH
Q ss_conf             6877764321000----013---5100---------------5967763----------021101279999999999997
Q gi|254780573|r  327 LTEAEILLSKWPQ----TST---SKGI---------------IDPAVLS----------ALYNDLNTVSAIQALHKLARE  374 (461)
Q Consensus       327 L~~A~~~l~kl~~----~~~---~~~~---------------~~~~f~~----------AL~DDLNTp~ALa~L~~lvk~  374 (461)
T Consensus       722 ~~~v~~~~~~~~~N~~~Fl~~YanL~~f~p~~~~~~~~~~~~~Drw~L~~l~~l~~~v~~~~e~Y~f~~~~~~l~~F~~~  801 (938)
T TIGR00392       722 LKQVAEKYRKIRWNTYRFLLTYANLDKFDPEEKAVAVEKFRELDRWILSRLNSLVEEVNEALEKYNFHKVLRALQDFIVE  801 (938)
T ss_pred             HHHHHHHHHHHHHHHHHHHHHHHHHHCCCCCCCCCCHHCCCHHHHHHHHHHHHHHHHHHHHHHCCCHHHHHHHHHHHHHH
T ss_conf             99999987688999999999988760778730023112030113999999999999999986263246788889876312