>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=97.30 E-value=0.00034 Score=49.71 Aligned_cols=279 Identities=20% Similarity=0.302 Sum_probs=130.1 Q ss_pred CEEEECCCHHHHHHHHHHHHCC---CCEEEEEC------C---CCCEEEEEEC-C-CCHHHH-------------HH--- Q ss_conf 6899889867999999999889---92999977------8---7861464356-8-270889-------------99--- Q gi|254781055|r 6 DLVVIGAGSSGVRSARLAAQLG---KKVAICEE------Y---RVGGTCVIRG-C-IPKKLM-------------FY--- 55 (461) Q Consensus 6 DvvIIG~GpaG~~aA~~la~~g---~kV~liE~------~---~~GGtC~~~G-C-iPsK~l-------------~~--- 55 (461) 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 HH-----HHHHHHHHHHCCCEECC--C--------------------------------CCCCHHHHHHHHHHHH----- Q ss_conf 99-----99999984101773637--7--------------------------------5449999999999999----- Q gi|254781055|r 56 AS-----QYSEYFEDSQGFGWSVD--H--------------------------------KSFDWQSLITAQNKEL----- 91 (461) Q Consensus 56 ~a-----~~~~~~~~~~~~g~~~~--~--------------------------------~~~d~~~~~~~~~~~~----- 91 (461) T Consensus 81 Ave~~~~~AP~~v~eLe~wG~PfSR~~kGDRmaiinaqkttiteeDfRDG~IaQR~FGG~~~~~Gg~~a~RTcyAADkTG 160 (636) T TIGR01812 81 AVEYMCKEAPKAVLELERWGVPFSRLPKGDRMAIINAQKTTITEEDFRDGRIAQRPFGGASFDYGGAAARRTCYAADKTG 160 (636) T ss_pred HHHHHHHHCCHHHHHHHHCCCCCCCCCCCCEEEEEECCCCEECCCCCCCCCEEECCCCCCCCCCCCCHHHHHHHHHCCCC T ss_conf 99999851517899997378985678677647776245420020115588353437888886556622213420012113 Q ss_pred -HHHHHHHHHHHCCCCEEECCCC-C--CCCC-CC--CC---CC---CCCC-CCEEEEEEEECCCCCEEEEE-ECCCCCCC Q ss_conf -8554668864300332001223-3--2222-22--22---22---2322-11001112322776402332-03762211 Q gi|254781055|r 92 -SRLESFYHNRLESAGVEIFASK-G--ILSS-PH--SV---YI---ANLN-RTITSRYIVVSTGGSPNRMD-FKGSDLCI 156 (461) Q Consensus 92 -~~l~~~~~~~l~~~gv~vi~g~-a--~~~~-~~--~v---~V---~~~~-~~i~a~~iiIATGs~p~~p~-i~g~~~~~ 156 (461) T Consensus 161 h~~LHTLye~~l~~~~V~ff~E~fa~~L~~~~~~GP~~~Gvva~~l~~G~~~~~~AKaVv~ATGG~GR~Y~~~tTNa~~~ 240 (636) T TIGR01812 161 HALLHTLYEQCLKLDGVEFFNEYFALDLILDQDGGPRVRGVVAYDLKTGEIVFFRAKAVVLATGGYGRVYKFTTTNAHIN 240 (636) T ss_pred HHHHHHHHHHHHCCCCCEEEHHHHHHHHHHHCCCCCEEEEEEEEEECCCEEEEEEECCEEEEECCCHHHHCCCCCCCEEE T ss_conf 14789899998537994275388887788745898679999999805880899960748983065102103044544223 Q ss_pred CCCCC-------CC-CCCCCCCCCCCCCCCCCCHHHHHH----HCCCC------C---CCEEC-CCCCCCCC--CC---C Q ss_conf 23785-------11-233334432123454530112442----10122------1---00000-11112222--22---3 Q gi|254781055|r 157 TSDEI-------FS-LKSLPQSTLIIGGGYIAVEFAGIL----NSLGS------K---TTLVT-RGNSILSK--FD---S 209 (461) Q Consensus 157 ts~~~-------~~-l~~~P~~i~IiGgG~ig~E~A~~~----~~lG~------~---Vtli~-~~~~~l~~--~d---~ 209 (461) T Consensus 241 TGDG~A~AlraG~PqL~D--------------MEFvQFHPTGL~~sGiL~tEgcRGEGGyL~N~~GeRFM~ryGYAPetP 306 (636) T TIGR01812 241 TGDGLAMALRAGVPQLKD--------------MEFVQFHPTGLAPSGILITEGCRGEGGYLINKEGERFMERYGYAPETP 306 (636) T ss_pred CCCHHHHHHHHCCCCCCC--------------CCCEECCCCCCCCCCEEEEEEEECCCCEEECCCCCCCCCCCCCCCCCC T ss_conf 540688888734643168--------------440503674556677177401332761686787531034468887887 Q ss_pred CCCCCC-----CCCCCCCCCCCCCCCEEEECCCCCCCCEEEEEC-C-CCC---------------CCCCCEEC-CCCEEE Q ss_conf 212222-----222222233233220001102445761024312-7-532---------------22210000-152220 Q gi|254781055|r 210 DIRQGL-----TDVMISRGMQVFHNDTIESVVSESGQLKSILKS-G-KIV---------------KTDQVILA-VGRTPR 266 (461) Q Consensus 210 ~~~~~~-----~~~l~~~Gv~i~~~~~v~~i~~~~~~~~~~~~~-g-~~~---------------~~D~vl~a-~Gr~Pn 266 (461) T Consensus 307 ~k~eLApRDvVSRa~~---~EireGRGv~~~-~~k~~v~LDLrHLGee~i~~RLP~i~E~A~~f~GVDPv~~pWiPVrPt 382 (636) T TIGR01812 307 EKMELAPRDVVSRAMV---TEIREGRGVGSG-PGKDYVYLDLRHLGEEKIEERLPQIRELAKTFAGVDPVKEPWIPVRPT 382 (636) T ss_pred CCCCCCCCCHHHHHHH---HHHHHCCCCCCC-CCCCEEEEEHHHCCHHHHHHCCHHHHHHHHHHCCCCCCCCCCCCCCCC T ss_conf 5000478769999999---999844888988-788778876401347888520756899999704888300576264564 Q ss_pred ECCCCCCCCCCCCCCCCCCCCC-CCC-CCCEEEEEEECCCC Q ss_conf 0126841123211235433445-743-00003558712543 Q gi|254781055|r 267 TTGIGLEKVGVKMDENGFIITD-CYS-RTNVQSIFSLGDIS 305 (461) Q Consensus 267 ~~~l~L~~~gi~~~~~G~i~vd-~~~-~Ts~~~IyA~GDv~ 305 (461) T Consensus 383 ~---HY~MGGI~T~~~G~~~~~D~~~~~~iv~GLfAaGE~A 420 (636) T TIGR01812 383 A---HYSMGGIDTNYRGQVIGEDAKNNDSIVKGLFAAGECA 420 (636) T ss_pred C---CCCCCCEEECCCCEEECCCCCCCCCCCCCEEEEEEEE T ss_conf 4---4118278445842487016788886210102201022

HHsearch alignment for GI: 254781055 and conserved domain: TIGR01812