>TIGR02539 SepCysS Sep-tRNA:Cys-tRNA synthase; InterPro: IPR013375 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 . Many archaeal species lack cysteinyl-tRNA synthetase, an essential enzyme that provides Cys-tRNA(Cys) in other organisms. Instead, in a two step pathway, tRNA-Cys is acylated with O-phosphoserine (Sep) to form Sep-tRNA(Cys), which is subsequently converted to Cys-tRNA(Cys) . This pathway is also thought to function as the sole route of cysteine biosynthesis in these organisms. Several other archaeal species use both this pathway and direct tRNA(Cys) aminoacylation to synthesize Cys-tRNA(Cys), but this pathway appears to be the only route for cysteine biosynthesis. Proteins in this entry catalyse the second step in this pathway using pyridoxal phosphate and a sulphur donor to synthesize Cys from Sep while attached to the tRNA..

Probab=99.96 E-value=2.8e-29 Score=204.20 Aligned_cols=347 Identities=18% Similarity=0.259 Sum_probs=242.3 Q ss_pred CCEEEEEC-CCCCCCCHHHHHHHHHHHHHHCCCC-CCH-HHHHHHHHHHHHHHHH-HHHHHHCCCCCCCCCCCCCCHHHH Q ss_conf 86599766-8888989899999999998614986-602-6799999999999999-999998287976543346876898 Q gi|254781062|r 22 KPLIYFDN-AASAQKPQDVIDSIMCTYSHEYANI-HRG-LHYMANAVTDKYEKAR-DKVRRFINASSVKEIIFTRSATES 97 (406) Q Consensus 22 ~~~iYld~-a~~~~~~~~V~~a~~~~~~~~~~n~-~~~-~~~~~~~~~~~~~~aR-~~ia~~lga~~~~~v~ft~~~Te~ 97 (406) T Consensus 6 r~~iN~nPlQrGGvLt~~ArkAl~EfGDGYSVCDfC~G~Ld~v---~~PpI~~F~~daLA~FlG~D~---~R~t~GARe~ 79 (381) T TIGR02539 6 REFINLNPLQRGGVLTEAARKALVEFGDGYSVCDFCEGRLDEV---TKPPIKDFLEDALAEFLGMDV---VRVTHGAREG 79 (381) T ss_pred CCCCCCCCCCCCCCCHHHHHHHEEEECCCCEEEECCCCEECCC---CCCCHHHHHHHHHHHHHCCCE---EECCCCCCHH T ss_conf 2131678434688783778710042268523853038770352---588310004554266727974---5406775024 Q ss_pred HHHHHHHHHHHHHHCCCCCCCCHHHHHHHHHHCCCCCCCCCCCCCCCC-CC--CCCCCHHHHHHHHCCC-------CCCC Q ss_conf 765432234443201344345401100001000012222322222222-22--2221025788751023-------3443 Q gi|254781062|r 98 INLVSYGWGARHISTGDEIVLSVMEHHSNIIPWYFLRQRRGASLVWVP-ID--NQGFFHIDEFKNRLTE-------RTKL 167 (406) Q Consensus 98 ~n~~~~~~~~~~~~~gd~Vi~s~~eh~s~~~~~~~~~~~~G~~v~~i~-~~--~~g~id~~~l~~~i~~-------~t~l 167 (406) T Consensus 80 KfaVMhal----C~~GD~vV~D~~AHYtsy----vAAEragl~v~eVPy~~g~P~Y~v~~e~Y~~viee~~d~~G~~~~L 151 (381) T TIGR02539 80 KFAVMHAL----CKEGDVVVLDGLAHYTSY----VAAERAGLNVKEVPYETGHPEYKVDPEGYKEVIEEVEDESGKPVAL 151 (381) T ss_pred HHHHHHHH----CCCCCEEEECCCCCHHHH----HHHHHCCCEEEECCCCCCCCEEEECHHHHHHHHHHHHCCCCCCCEE T ss_conf 57887640----899898998587454458----9997549727881655888607641667888886552027988348 Q ss_pred CCCCCCCCCCCCCCCCCCEECCCCCCCCCCCCCCCCCCCCCCCCHHHHCCCCCCCCCCC-C--CCCCCCCHHHCCCCCCC Q ss_conf 32222222233333332100023444431012332000111000011001122234322-2--35444310002566631 Q gi|254781062|r 168 IAITHMSNVLGTVIPIKEICRIAHERNIPVLVDGSQGSVHNFVDVQDIDCDWYIITGHK-L--YGPSGIGGLYSKESRLN 244 (406) Q Consensus 168 v~i~~~~~~tG~~~pi~~I~~~~~~~g~~~~vD~aq~~g~~~id~~~~~~D~~~~S~hK-~--~Gp~G~G~l~~~~~~~~ 244 (406) T Consensus 152 allThvDG~YGNL~DA~kva~vc~~~gvPlLLNCAY~vGRmPv~~ke~~~DFiVGSGHKSMAASaP--~GvLa~~eE~~~ 229 (381) T TIGR02539 152 ALLTHVDGEYGNLADAKKVAKVCREKGVPLLLNCAYTVGRMPVSAKEIKADFIVGSGHKSMAASAP--CGVLAMSEEWED 229 (381) T ss_pred EEEEECCCCCCCCHHHHHHHHHHHHCCCCEEECCCCEEEEECCCCCCCCCCEEEECCCCHHHHCCC--EEECCCCCCCCC T ss_conf 998402688675112456876654207862212450521003157777876778068513221266--002145422234 Q ss_pred CC-EEECCCCEEEEEEECCCCCCCCCHHCCCCC-CCCCHHHHHHHHHCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCEE Q ss_conf 00-121145303433202453003310000012-2120245664210123322222222222222222222222222101 Q gi|254781062|r 245 EM-DPFMGGSEMIADVTQDMVTYADLPYRFEPG-TPPISQAIALGVALDYVEKIDRKSIFSYERELARYVRSRLKEVRGM 322 (406) Q Consensus 245 ~~-~p~~~g~~~~~~~~~~~~~~~~~~~r~e~G-t~~~~~~~al~~al~~~~~~g~~~i~~~~~~l~~~l~~~L~~~~g~ 322 (406) T Consensus 230 ~v~r~S----slrGdvsG~~~~~KEvEl---LGCT~rGap~~TlmASfP~Vve--RV~~Wd~Ev~ktRy~v~eLE~igG~ 300 (381) T TIGR02539 230 KVLRKS----SLRGDVSGRKFPVKEVEL---LGCTSRGAPIVTLMASFPHVVE--RVKRWDEEVKKTRYFVAELEDIGGF 300 (381) T ss_pred CHHCCC----CCCCCCCCCCCCCCEEEE---CCCCCCHHHHHHHHHCCCHHHH--HCCCHHHHHHHHHHHHHHHHHCCCE T ss_conf 011023----210033663447412774---4863240479999732810112--2023156677765788876421788 Q ss_pred EECCCCCCCCCEEEEEECCC---------CHHHHHHHHHHCCCE-EEECCHHHHHHHHHCCCCCEEEEEECCCCCHHHHH Q ss_conf 32268521586799980899---------999999999878969-99752112788997289957999935888999999 Q gi|254781062|r 323 QLVNESLEDSPIISFRLGNI---------HPYDLALFLDGEGIA-IRAGTHCANPLLKFLGIDSLCRASLAMYNTYEEAD 392 (406) Q Consensus 323 ~i~~~~~~~~~iv~~~~~~~---------~~~~v~~~L~~~gI~-v~~G~~ca~~~~~~~g~~~~iRiS~~~~nt~edid 392 (406) T Consensus 301 ~QlG~kPk~HDLv~FEtPgf~Eia~~~kr~GyFLY~ELKkRgi~GI~~G------------~Tk~~K~SvY-GL~~Eqv~ 367 (381) T TIGR02539 301 KQLGVKPKEHDLVKFETPGFHEIAKKHKRRGYFLYEELKKRGIVGIRSG------------QTKEIKLSVY-GLTKEQVE 367 (381) T ss_pred EECCCCCCCCCCEEECCCCCHHHHCCCCCCCCCHHHHHHHCCCEECCCC------------CCEEEEEEEE-CCCCCHHH T ss_conf 8648688825641444884013414487977640566531583001788------------7427764331-27521144 Q ss_pred HHHHHHHHHHHHHC Q ss_conf 99999999999719 Q gi|254781062|r 393 KFIETLKKSIQFFQ 406 (406) Q Consensus 393 ~~i~~l~~~i~~l~ 406 (406) T Consensus 368 ~Vv~sf~eI~e~~~ 381 (381) T TIGR02539 368 YVVDSFKEIVEEYK 381 (381) T ss_pred HHHHHHHHHHHHCC T ss_conf 44678999998549

HHsearch alignment for GI: 254781062 and conserved domain: TIGR02539