>TIGR00418 thrS threonyl-tRNA synthetase; InterPro: IPR002320 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 . Threonyl-tRNA synthetase (6.1.1.3 from EC) exists as a monomer and belongs to class IIa. The enzyme from Escherichia coli represses the translation of its own mRNA. The crystal structure of the complex between tRNA(Thr) and ThrRS show structural features that reveal novel strategies for providing specificity in tRNA selection. These include an amino-terminal domain containing a novel protein fold that makes minor groove contacts with the tRNA acceptor stem. The enzyme induces a large deformation of the anticodon loop, resulting in an interaction between two adjacent anticodon bases, which accounts for their prominent role in tRNA identity and translational regulation. A zinc ion found in the active site is implicated in amino acid recognition/discrimination . The zinc ion may act to ensure that only amino acids that possess a hydroxyl group attached to the beta-position are activated .; GO: 0004829 threonine-tRNA ligase activity, 0005524 ATP binding, 0006412 translation, 0006435 threonyl-tRNA aminoacylation, 0005737 cytoplasm.

Probab=100.00 E-value=2.3e-33 Score=235.83 Aligned_cols=370 Identities=17% Similarity=0.232 Sum_probs=243.8 Q ss_pred CCCCCCCCCCCCHHHHHHHHHHHHHHHHHHHHCCCEEEECCCHHHHHHHHCCCCCCCCCCCCEEEEECCCCCEEEECCCC Q ss_conf 10379987658866899999999999999998598480165202288752026755433322168986999889998888 Q gi|254780928|r 8 RAELPRGFADCPTKEIRIRNRILDSIRNIYENYGFDPIETPLLEYSDSLGKFLPDEDRPNKGVFSLQDDDGQWISLRYDL 87 (496) Q Consensus 8 ~~~~P~G~~D~~p~~~~~~~~i~~~l~~~f~~~G~~~I~tP~lE~~~~~~~~~~~~~~~~k~~y~f~D~~g~~l~LRpDl 87 (496) T Consensus 197 ~~~~gpG~~~WlPkG~~ir~~ledf~~~~~~~~Gy~~V~TP~m~~~~l~-~~sGH~~~Y~e~Mf~~~~~~~~~~~LkPMn 275 (595) T TIGR00418 197 EPEIGPGLPFWLPKGALIRNLLEDFVREKQIKRGYEEVETPIMYDSELW-EISGHWDHYKERMFPFTEEDNQEFMLKPMN 275 (595) T ss_pred CCCCCCCCEEECCCHHHHHHHHHHHHHHHHHHCCCCCCCCCEECCCCCH-HHHHHHHHCCCCCCCCEEECCCCCCCCCCC T ss_conf 8320487414657646789999999999998758864157412156542-453054503423540101035303345677 Q ss_pred HHHHHHHHHHH-HHHCCCCHHHHHHH-HHHCCCCCCC--C--CCCCCCCCCHHHHHC-CCHH-HHH-HHHHHHHHHHHHC Q ss_conf 38999999951-12055411233101-3330258764--4--421111100012100-0024-578-8999999999751 Q gi|254780928|r 88 TAPLARYVAEN-FDTIVFPCRTYRIG-PVFRNEKHGP--G--RFRQFIQCDVDNVGS-SAET-ADA-EMCMMMADTLEAV 158 (496) Q Consensus 88 T~~~aR~~~~~-~~~~~~p~k~yy~g-~vfR~e~p~~--G--r~REf~Q~g~eiiG~-~~~~-~Da-Eii~l~~~~l~~l 158 (496) T Consensus 276 CpgH~~i~k~~~~SYR~LP~R~aE~g~~~hR~E~sG~L~GL~RvR~FT~dDaHifc~d~dQi~~E~~~~~~l~~~v~~~f 355 (595) T TIGR00418 276 CPGHILIFKSSLRSYRDLPLRIAELGTTVHRYEKSGALHGLKRVRGFTQDDAHIFCTDEDQIKSEIKNQFRLIQKVYSKF 355 (595) T ss_pred CHHHHHHHCCCCCCHHHCCCHHHHCCCEEEEEECCCCCCHHHHHHHCCCCCCCEEECCHHHHHHHHHHHHHHHHHHHHHH T ss_conf 54453300177777323350343318604788425421010164430699852453786779999999999999998872 Q ss_pred CCCCCCCEEECCCCHHHHHHHHHHCCCHHHHHHHHHHHHHHHHHCCCCCHHHHHHHHHHCCCCHHHHHHCCCCCCHHHHH Q ss_conf 88877711303660558999998325603564334555333220012896789986210165003555304899977899 Q gi|254780928|r 159 GIKRNDYHIGINNRKILDGILEKIGLHGDDKLNERLIVLRAIDKLDKFGLQGVKLLLGEGRTDNSGDFTKGANLTSEQID 238 (496) Q Consensus 159 gl~~~~~~I~in~~~il~~il~~lgi~~~~~~~~~~~~~~~idkl~k~~~~~~~~~l~~~~~~~~~~~~~~~~~~~~~~~ 238 (496) T Consensus 356 gf~--~~~~~LS~R~-----------Pe~~~K--------y~g~--d~~W~~~~~~l~~~l~~~~~~yei~~G~~AFYGP 412 (595) T TIGR00418 356 GFS--NYKYELSTRD-----------PENDKK--------YIGE--DELWEKAESALEEALKELGVDYEIDEGEGAFYGP 412 (595) T ss_pred CCC--CCEEEEEECC-----------CCCCCC--------CCCC--HHHHHHHHHHHHHHHHCCCCCEEEECCCCEEECC T ss_conf 884--2168998717-----------775455--------4588--7899999999999985079840550788113022 Q ss_pred HHHHHHCCCCHHHHHHHHHHHCCCHHHHHHHHHHHHHHHHHHHCCCCCCCCCCCHHHCCCCCCCCCEEEEEEECCCCCCC Q ss_conf 88874047856889989986035732588899999999998750888443001101001221234124899854666776 Q gi|254780928|r 239 IMVSFLSIDLEKSMHELYELVKGTIAGEKGFNELVVISELVRKSGYNSNRIKISSTIVRGLEYYTGCVYEAILGFPVMNE 318 (496) Q Consensus 239 ~~~~~~~~~~~~~~~~l~~~~~~~~~~~~~l~~l~~i~~~l~~~gv~~~~i~~Dl~lvRgLdYYTG~vFE~~~~~~~~~~ 318 (496) T Consensus 413 Ki---------------------Df~~~DaL~R~---------~--q~~TvQlDf~lP---------------------- 438 (595) T TIGR00418 413 KI---------------------DFQIKDALGRE---------W--QCATVQLDFELP---------------------- 438 (595) T ss_pred EE---------------------EEEEEECCCCH---------H--HCCCEEEECCCC---------------------- T ss_conf 26---------------------88875101764---------2--588148871588---------------------- Q ss_pred CCCCCCEEEECCCCCCC-CCCCCC--CCCCCCC---CEEEECCHHHHHHHHHCC-CCC-----CCCCCCCEEEEEEECCC Q ss_conf 76663101100323235-521112--3456774---213311016899999736-877-----66555771489982697 Q gi|254780928|r 319 KQKPVVFGSVGGGGRYD-GLVSRF--KGQNVPA---TGFSIGISRLIVALKSLE-SST-----NNIKEMGPVLITTMDHD 386 (496) Q Consensus 319 ~~~~~~~~aI~~GGRYD-~L~~~f--~~~~~pa---vGfaigverl~~~l~~~~-~~~-----~~~~~~~~v~V~~~~~~ 386 (496) T Consensus 439 -------------eRF~l~Y~~~dqd~~~~~Pv~IHra~~GS~ERfi~iL~E~~~G~fde~~PMLP~WLaP~QV~viPV~ 505 (595) T TIGR00418 439 -------------ERFDLTYINEDQDNKEKRPVMIHRAILGSIERFIAILLEKYAGAFDERLPMLPLWLAPVQVVVIPVS 505 (595) T ss_pred -------------CCCCCEEEEECCCCCCCCCEEEECCCCHHHHHHHHHHHHHHHHHHHCCCCCCCEECCCEEEEEEECC T ss_conf -------------7203148420367870067789804400589999999987522211468988542176238997057 Q ss_pred -HHHHHHHHHHHHHHHHCCCEEEEEECCCCCHHHHHHHHHHCCCCEEEEECHHHHHC--CCEEEEECC---CCCEEEEEC Q ss_conf -68999999999999987983999718999988999999877998999988728748--818997878---883643311 Q gi|254780928|r 387 -SDSLSKYQMYTQMLRTAGIRAEMFLGSSKNFGNQLKYADRRNCPLAIIQGTGERSR--GMLQIKDLA---KGKELSREI 460 (496) Q Consensus 387 -~~~~~~~~~ia~~Lr~~Gi~~e~~~~~~~sl~~~~~~A~~~g~~~viiig~~e~~~--~~v~vK~l~---~g~q~~~~~ 460 (496) T Consensus 506 i~~h~~yA~kv~~~L~~~giRv~~D~r~e-~lgkKIR~a~~~kiPy~~V~Gd~E~e~~K~~v~vR~~~t~k~~~------ 578 (595) T TIGR00418 506 IEKHLDYAKKVAEKLKKEGIRVDVDDRNE-RLGKKIREAQKQKIPYMLVVGDKEMEELKEAVNVRTRKTLKGQK------ 578 (595) T ss_pred HHHHHHHHHHHHHHHHHCCCEEEECCCCC-CHHHHHHHHHCCCCCEEEEECCHHHHCCCCEEEECCHHHHCCCC------ T ss_conf 78899999999999985797798838888-01332022013220679998730231389668522402104631------ Q ss_pred CCHHHHHHCCCCCEEECHHHHHHHHHH Q ss_conf 201443202335103079999999999 Q gi|254780928|r 461 KNNESWREARVAQITIPISELVSTVKK 487 (496) Q Consensus 461 ~~~~~~~~~~~~q~~v~~~~l~~~~~~ 487 (496) T Consensus 579 ------------~~~m~~~E~~~~~~~ 593 (595) T TIGR00418 579 ------------LEKMSLDEFLEKVRK 593 (595) T ss_pred ------------EEEECHHHHHHHHHH T ss_conf ------------014309999999973

HHsearch alignment for GI: 254780928 and conserved domain: TIGR00418