>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=99.93 E-value=2.7e-25 Score=173.00 Aligned_cols=336 Identities=21% Similarity=0.279 Sum_probs=235.6 Q ss_pred CEECCCCC-CCCCCHHHHHHHHHHHHHCCC----CCHHHHHHHHHHHHHHHHHHH-HHHHCCCCHHHEEEECCHHHHHHH Q ss_conf 00121578-889898999999999964288----523658999999999999999-999729897789886685387644 Q gi|254781091|r 4 RVYLDWNA-TAPLLEVVRQSFVKSLDFYGN----PSSVHKEGQKTRLYIEESRRI-IADFCGAKPDHVVFTSSATEAANW 77 (383) Q Consensus 4 ~iYlD~aa-ttp~~~~v~~a~~~~~~~~~n----~~s~h~~~~~~~~~~e~aR~~-ia~~~g~~~~ei~ft~~~T~a~~~ 77 (383) T Consensus 8 ~iN~nPlQrGGvLt~~ArkAl~EfGDGYSVCDfC~G~Ld~v---~~PpI~~F~~daLA~FlG~D~~R--~t~GARe~Kfa 82 (381) T TIGR02539 8 FINLNPLQRGGVLTEAARKALVEFGDGYSVCDFCEGRLDEV---TKPPIKDFLEDALAEFLGMDVVR--VTHGAREGKFA 82 (381) T ss_pred CCCCCCCCCCCCCHHHHHHHEEEECCCCEEEECCCCEECCC---CCCCHHHHHHHHHHHHHCCCEEE--CCCCCCHHHHH T ss_conf 31678434688783778710042268523853038770352---58831000455426672797454--06775024578 Q ss_pred HHHHHHHHCCCCCCCCEEEECCCCCCCCCCCCCCCCCCCCCCCC-C--CCCCCCCHHHHHHHHHHHCC--CCCCEEEEEC Q ss_conf 55654421022456645873332122111222222222222222-2--22211102345532443113--5653265403 Q gi|254781091|r 78 VLTPHFYQGSHKISIDSLYISAIEHPAVYAGGHFPSHKIHKIPV-L--SKGIVDIQALTDFLEQRNST--CGIPMIAVMF 152 (383) Q Consensus 78 ~i~~~~~~~~~~~~~~~ii~s~~eH~s~~~~~~~~~~~v~~v~~-~--~~g~i~~~~l~~~i~~~t~~--~~~~LVs~~~ 152 (383) T Consensus 83 VMhalC~------~GD~vV~D~~AHYtsyvAAEragl~v~eVPy~~g~P~Y~v~~e~Y~~viee~~d~~G~~~~LallTh 156 (381) T TIGR02539 83 VMHALCK------EGDVVVLDGLAHYTSYVAAERAGLNVKEVPYETGHPEYKVDPEGYKEVIEEVEDESGKPVALALLTH 156 (381) T ss_pred HHHHHCC------CCCEEEECCCCCHHHHHHHHHCCCEEEECCCCCCCCEEEECHHHHHHHHHHHHCCCCCCCEEEEEEE T ss_conf 8764089------9898998587454458999754972788165588860764166788888655202798834899840 Q ss_pred CCCCCCCCCCHHHHHHHHCCCCCCCCCCCCCCCCCCCCCCCCCCCEEEEECCCC-C--CCCCCCHHHHCCCCCCCC---C Q ss_conf 434443332112356520344653344432336554444433431068730543-3--223432011014574201---2 Q gi|254781091|r 153 VNNETGVIQPIKEIAQIVKEYQGILVVDAVQAAGRIPLSIEEIKADFLIISSHK-L--GAPVGAGALVFREDILLP---S 226 (383) Q Consensus 153 ~~n~tG~i~pi~~I~~~~~~~g~~~~vD~aqa~g~~~id~~~~~~D~~~~S~hK-~--~GP~G~G~L~~r~~~~~~---~ 226 (383) T Consensus 157 vDG~YGNL~DA~kva~vc~~~gvPlLLNCAY~vGRmPv~~ke~~~DFiVGSGHKSMAASaP--~GvLa~~eE~~~~v~r~ 234 (381) T TIGR02539 157 VDGEYGNLADAKKVAKVCREKGVPLLLNCAYTVGRMPVSAKEIKADFIVGSGHKSMAASAP--CGVLAMSEEWEDKVLRK 234 (381) T ss_pred CCCCCCCCHHHHHHHHHHHHCCCCEEECCCCEEEEECCCCCCCCCCEEEECCCCHHHHCCC--EEECCCCCCCCCCHHCC T ss_conf 2688675112456876654207862212450521003157777876778068513221266--00214542223401102 Q ss_pred CCCCCC----CCCCCCCCCCCCCCCCCCHHHHHHCCCCH------HHHHHHHHHHHHHHHHHHHHHHHHCCCCCCCCCCC Q ss_conf 212247----74212222222112221001221100100------24565321012333344444321000122322110 Q gi|254781091|r 227 PLLRGG----DQEKGQRAGTENYAVIGGFAVAAQQMVKD------IQKRSSRVFAIRDYLEQELKKLIPNIIIYGKDAER 296 (383) Q Consensus 227 p~~~Gg----~~e~~~~~GT~~~~~i~~~~~al~~~~~~------~~~~~~~~~~L~~~l~~~l~~~~~~~~i~~~~~~~ 296 (383) T Consensus 235 SslrGdvsG~~~~~KE----vElLGCT~rGap~~TlmASfP~VveRV~~Wd~Ev~ktRy~v~eLE~-igG~~QlG~kPk~ 309 (381) T TIGR02539 235 SSLRGDVSGRKFPVKE----VELLGCTSRGAPIVTLMASFPHVVERVKRWDEEVKKTRYFVAELED-IGGFKQLGVKPKE 309 (381) T ss_pred CCCCCCCCCCCCCCCE----EEECCCCCCHHHHHHHHHCCCHHHHHCCCHHHHHHHHHHHHHHHHH-CCCEEECCCCCCC T ss_conf 3210033663447412----7744863240479999732810112202315667776578887642-1788864868882 Q ss_pred CCCEEEEEECCC---------CHHHHHHHHHHCCCE-EEECHHHCCCCCCCCHHHHHCCCCCCCCEEEEEECCCCCHHHH Q ss_conf 365228985799---------999999998758969-9871133886433101467628887476599990788899999 Q gi|254781091|r 297 ISNTCCFSIPFL---------KAEVLQIALDLEGIA-VSAGSACSSGKIKKNHVLAAMGFDTSQGAVRVSCGDSTTQEDI 366 (383) Q Consensus 297 ~~~i~~~~~~~~---------~~~~v~~~l~~~gI~-v~~G~~C~~~~~~~~~vl~~~g~~~~~g~vRiS~~~~nT~~dI 366 (383) T Consensus 310 HD-Lv~FEtPgf~Eia~~~kr~GyFLY~ELKkRgi~GI~~------------------G~T---k~~K~SvY-GL~~Eqv 366 (381) T TIGR02539 310 HD-LVKFETPGFHEIAKKHKRRGYFLYEELKKRGIVGIRS------------------GQT---KEIKLSVY-GLTKEQV 366 (381) T ss_pred CC-CEEECCCCCHHHHCCCCCCCCCHHHHHHHCCCEECCC------------------CCC---EEEEEEEE-CCCCCHH T ss_conf 56-4144488401341448797764056653158300178------------------874---27764331-2752114 Q ss_pred HHHHHHHHHHHHHH Q ss_conf 99999999999862 Q gi|254781091|r 367 DIFLNALQKIIRTS 380 (383) Q Consensus 367 d~l~~~L~~iv~~~ 380 (383) T Consensus 367 ~~Vv~sf~eI~e~~ 380 (381) T TIGR02539 367 EYVVDSFKEIVEEY 380 (381) T ss_pred HHHHHHHHHHHHHC T ss_conf 44467899999854

HHsearch alignment for GI: 254781091 and conserved domain: TIGR02539