>TIGR01812 sdhA_frdA_Gneg succinate dehydrogenase or fumarate reductase, flavoprotein subunit; InterPro: IPR014006 Succinate:quinone oxidoreductase (1.3.5.1 from EC) refers collectively to succinate:quinone reductase (SQR, or Complex II) and quinol:fumarate reductase (QFR) . SQR is found in aerobic organisms, and catalyses the oxidation of succinate to fumarate in the citric acid cycle and donates the electrons to quinone in the membrane. QFR can be found in anaerobic cells respiring with fumarate as terminal electron acceptor. SQR and QFR are very similar in composition and structure, despite catalysing opposite reactions in vivo. They are thought to have evolved from a common ancestor, and in Escherichia coli they are capable of functionally replacing each other . Succinate:quinone oxidoreductases consist of a peripheral domain, exposed to the cytoplasm in bacteria and to the matrix in mitochondria, and a membrane-integral anchor domain that spans the membrane (Fig. 1). The peripheral part, which contains the dicarboxylate binding site, is composed of a flavoprotein subunit, with one covalently bound FAD, and an iron-sulphur protein subunit containing three iron-sulphur clusters. The membrane-integral domain functions to anchor the peripheral domain to the membrane and is required for quinone reduction and oxidation. The anchor domain shows the largest variability in composition and primary sequence, being composed either of one large subunit, or two smaller subunits, which may, or may not, contain protoheme groups. This entry represents the flavoprotein subunit found in both the SQR and QFR enzymes. This subunit contains an N-terminal domain which binds the FAD cofactor, a central catalytic domain with an unsual fold, and a C-terminal domain whose role is unclear , , . The dicarboxylate binding site is located between the FAD and catalytic domains..

Probab=100.00 E-value=0 Score=1455.54 Aligned_cols=586 Identities=56% Similarity=0.900 Sum_probs=555.7 Q ss_pred CEEEECCCHHHHHHHHHHHHCC---CCEEEEECCCCCCCCCHHCCCCEEEECC-CCC-CCCHHHHHHHHHHHCCCCCCHH Q ss_conf 5889899689999999999889---8299998689885210411653425137-899-9999999998998458877999 Q gi|254781043|r 19 DVVVVGAGGAGLRATLGMAEKG---FKTACITKVFPTRSHTVAAQGGIAASLA-NMT-PDSWQWHLYDTIKGSDWLGDVD 93 (611) Q Consensus 19 DVlVIG~G~AGl~AAi~A~e~G---~~V~lieK~~~~~g~s~~A~GGi~a~~~-~~~-~Ds~~~~~~Dt~~~g~~l~d~~ 93 (611) T Consensus 1 D~vIVGaGgAGlRAA~e~a~~gPp~~~~AvisKvyP~RSHtvAAQGG~~Aal~~n~d~~D~~e~H~yDTVKGsDyLaDQD 80 (636) T TIGR01812 1 DVVIVGAGGAGLRAAVEAAKAGPPNLNVAVISKVYPTRSHTVAAQGGIAAALANNVDPDDSWEWHAYDTVKGSDYLADQD 80 (636) T ss_pred CEEEECCCHHHHHHHHHHHHCCCCCCEEEEEECCCCCCCCCHHHHHHHHHHHCCCCCCCCCCCCCEEEEECCCCCCHHHH T ss_conf 97888186689999999973577961079995569885201535678999957786432072123041101442132589 Q ss_pred HHHHHHHHHHHHHHHHHHCCCCCCCCC---------------------CCCEEEECCCCCCCCCCCCCCCCEEEEECCCC Q ss_conf 999999988999999998699813279---------------------98551001464114567876564079866654 Q gi|254781043|r 94 AIQYLAMEAPQSVYELEHYGVPFSRNE---------------------AGKIYQRPFGGHMQNYGEGPPVQRTCAAADRT 152 (611) Q Consensus 94 lv~~~~~~a~~~i~~Le~~Gv~f~r~~---------------------~G~~~~~~~gg~~~~~~~g~~~~R~~~~~d~t 152 (611) T Consensus 81 Ave~~~~~AP~~v~eLe~wG~PfSR~~kGDRmaiinaqkttiteeDfRDG~IaQR~FGG~~~~~G-g~~a~RTcyAADkT 159 (636) T TIGR01812 81 AVEYMCKEAPKAVLELERWGVPFSRLPKGDRMAIINAQKTTITEEDFRDGRIAQRPFGGASFDYG-GAAARRTCYAADKT 159 (636) T ss_pred HHHHHHHHCCHHHHHHHHCCCCCCCCCCCCEEEEEECCCCEECCCCCCCCCEEECCCCCCCCCCC-CCHHHHHHHHHCCC T ss_conf 99999851517899997378985678677647776245420020115588353437888886556-62221342001211 Q ss_pred CHHHHHHHHHHHHHC-CCEEECCCEEEEEEECCCC--CCEEEEEEEECCCEEEEECCCCEEEECCCCCCCCC-CCCCCCE Q ss_conf 266789999998731-2303113156520001344--30124689805870899506724741576565433-4210640 Q gi|254781043|r 153 GHAILHTLYGQALKN-NAEFFIEYFALDLIINSEG--CCVGVVAWQLETGEIHRFSAKLVVLATGGYGRAYF-SATSAHT 228 (611) Q Consensus 153 G~~i~~~L~~~~~~~-gv~i~~~~~~~~Li~d~dG--~V~Gav~~~~~~G~~~~i~AkaVILATGG~~~ly~-~~t~~~~ 228 (611) T Consensus 160 Gh~~LHTLye~~l~~~~V~ff~E~fa~~L~~~~~~GP~~~Gvva~~l~~G~~~~~~AKaVv~ATGG~GR~Y~~~tTNa~~ 239 (636) T TIGR01812 160 GHALLHTLYEQCLKLDGVEFFNEYFALDLILDQDGGPRVRGVVAYDLKTGEIVFFRAKAVVLATGGYGRVYKFTTTNAHI 239 (636) T ss_pred CHHHHHHHHHHHHCCCCCEEEHHHHHHHHHHHCCCCCEEEEEEEEEECCCEEEEEEECCEEEEECCCHHHHCCCCCCCEE T ss_conf 31478989999853799427538888778874589867999999980588089996074898306510210304454422 Q ss_pred ECCHHHHHHHHHCCC-CCCCCCCCCCCCCCCCCEEECCCCCCCCCEEEEECCCCCCCCC--CC---CCCCCCCCCCEEHH Q ss_conf 144488788751365-3333222328884422014304566557808983268612554--07---65100475201115 Q gi|254781043|r 229 CTGDGAGMVARAGLP-LQDMEFVQFHPTGIYGAGCLITEGARGEGGYLVNSKGERFMER--YA---PSAKDLASRDVVSR 302 (611) Q Consensus 229 ~tGdG~~mA~~aGa~-l~~mEf~qfhPt~~~~~~~l~~~~~rg~G~~l~n~~Gerf~~~--y~---~~~~el~~rd~~s~ 302 (611) T Consensus 240 ~TGDG~A~AlraG~PqL~DMEFvQFHPTGL~~sGiL~tEgcRGEGGyL~N~~GeRFM~ryGYAPetP~k~eLApRDvVSR 319 (636) T TIGR01812 240 NTGDGLAMALRAGVPQLKDMEFVQFHPTGLAPSGILITEGCRGEGGYLINKEGERFMERYGYAPETPEKMELAPRDVVSR 319 (636) T ss_pred ECCCHHHHHHHHCCCCCCCCCCEECCCCCCCCCCEEEEEEEECCCCEEECCCCCCCCCCCCCCCCCCCCCCCCCCCHHHH T ss_conf 35406888887346431684405036745566771774013327616867875310344688878875000478769999 Q ss_pred HHHHHHHHCCCCC--CCCCEEEEEECCCCHHHHHHHHHHHHHHHHHHCCCCCCCCE-EEEECCCCCCCCCCCCCCCCEEE Q ss_conf 6889988178888--88874688611179899999853799999764367865440-67520331001234215771585 Q gi|254781043|r 303 CMMMEIREGRGVG--KSKDHIHLYLNHLDPAVLQERLPGISESARIFAGVDVTRDP-IPVIPTVHYNMGGIPTNYWGEVL 379 (611) Q Consensus 303 ai~~ei~~g~g~~--~~~~~v~ld~~~~~~~~l~~~~~~~~~~~~~~~g~D~~~~~-i~v~p~~hy~~GGi~vd~~g~v~ 379 (611) T Consensus 320 a~~~EireGRGv~~~~~k~~v~LDLrHLGee~i~~RLP~i~E~A~~f~GVDPv~~pWiPVrPt~HY~MGGI~T~~~G~~~ 399 (636) T TIGR01812 320 AMVTEIREGRGVGSGPGKDYVYLDLRHLGEEKIEERLPQIRELAKTFAGVDPVKEPWIPVRPTAHYSMGGIDTNYRGQVI 399 (636) T ss_pred HHHHHHHHCCCCCCCCCCCEEEEEHHHCCHHHHHHCCHHHHHHHHHHCCCCCCCCCCCCCCCCCCCCCCCEEECCCCEEE T ss_conf 99999984488898878877887640134788852075689999970488830057626456444118278445842487 Q ss_pred CCCCCCCCCCCCCEEECCCCCCCCCCCCCCCCCCCCCCCCCCCHHHHHHHHHHHHHCCCC----CCCCCHHHHHHHHHHH Q ss_conf 377888533227603402122033566430476432222223215677556654202656----6764002357888631 Q gi|254781043|r 380 DANSKNPERFAPGLMAIGEAGCASVHGANRLGSNSLIDLVVFGRAAVIRASEMIDKSSPI----PSLDISSCDRIMDRFD 455 (611) Q Consensus 380 ~~~~~~~~t~i~GLyAaGe~a~~g~hGanrlggnsl~~~~vfG~~Ag~~aa~~~~~~~~~----~~~~~~~~~~~~~~~~ 455 (611) T Consensus 400 ~~D~~~~~~iv~GLfAaGE~ACVSVHGANRLGsNSLle~vVFGr~aG~~~ae~~~~~~~~neL~~~~~~~~~~~~~~~~~ 479 (636) T TIGR01812 400 GEDAKNNDSIVKGLFAAGECACVSVHGANRLGSNSLLELVVFGRIAGEAAAEYLAKTGVDNELAADLEEEEVKKEEALID 479 (636) T ss_pred CCCCCCCCCCCCCEEEEEEEEECCCCCCCCCCHHHHHHHHHHHHHHHHHHHHHHHCCCCCCCCCCCCCHHHHHHHHHHHH T ss_conf 01678888621010220102220341213060567999999979999999999860688631133454458999999999 Q ss_pred CCCC-CCCCCCHHHHHHHHHHHHHCCCEEEECHHHHHHHHHHHHHHHHHH-HCCCCCCCCCCCCHHHHHHHHHHHHHHHH Q ss_conf 0103-788713689998788766509726875899999999999999998-41515787754588999999888899999 Q gi|254781043|r 456 RLRH-ADGHVPTAALREKMQRAMQLDAGVFRTQDSLSDGCRNLSCLWDEM-ADLKVHDRSLIWNSDLVETLELQNLMINA 533 (611) Q Consensus 456 ~~~~-~~g~~~~~~i~~~Lq~iM~~~~gi~R~~~~L~~al~~L~~l~~~~-~~i~~~d~~~~~n~el~~~~el~~~l~~A 533 (611) T Consensus 480 ~~~~~~~~~~~~a~ir~~l~~~M~~~~gvFR~~~~l~~a~~~i~eL~eR~~~~v~i~DKs~~fNTdL~~AlEL~nlL~lA 559 (636) T TIGR01812 480 LLKEEGNGGERVAQIREELQETMEANVGVFRTEELLKKAVDEIEELRERRYKNVKINDKSKVFNTDLLEALELGNLLDLA 559 (636) T ss_pred HHCCCCCCCCCHHHHHHHHHHHHHCCCEEEECCHHHHHHHHHHHHHHHCCCCCEEEEECCCEECHHHHHHHHHHHHHHHH T ss_conf 73036788735799999998886658579877322788999999986100164567405421236688899776458999 Q ss_pred HHHHHHHHCCCCCCCCEECCCCC--CCCCCCCCCHHHCEEEEEEEECC---CCEEEEEEECCCCCCCCCCCCEEECCCCC Q ss_conf 99999996262550462353377--88766688032135699998468---98059999447444256755000027721 Q gi|254781043|r 534 IATVYSAEARKESRGSHAREDFK--DGEFGGRDDVNWRKHSLCWVDWN---TGKIKLDYRPVHTELLCGGVDYSKIAPKA 608 (611) Q Consensus 534 e~~~~aal~R~ESRG~H~R~DyP--e~~~~~rDD~nwl~h~~~~~~~~---~g~~~~~~~Pv~~~~~~~~~~~~~~~p~~ 608 (611) T Consensus 560 ev~a~gAl~R~ESRGAH~ReDyPCt~-----RDD~NwlkHTla~~~~~~d~~~~~~l~Y~pV~~~~~~~a-r~~Ay~P~~ 633 (636) T TIGR01812 560 EVVAAGALNRKESRGAHAREDYPCTE-----RDDENWLKHTLAYYDNNEDKEGTPKLEYKPVTITKLEIA-RVSAYEPKE 633 (636) T ss_pred HHHHHHHHCCCCCCCCCCCCCCCCCC-----CCCHHHHHCCCCCCCCCCCCCCCEEEEEECCCCCCCEEE-ECCCCCCCC T ss_conf 99999976085466777513488777-----673136642035378886634560255521312332010-005658777 Q ss_pred CCC Q ss_conf 679 Q gi|254781043|r 609 RVY 611 (611) Q Consensus 609 R~Y 611 (611) T Consensus 634 R~Y 636 (636) T TIGR01812 634 RKY 636 (636) T ss_pred CCC T ss_conf 889

HHsearch alignment for GI: 254781043 and conserved domain: TIGR01812