>TIGR01341 aconitase_1 aconitate hydratase 1; InterPro: IPR006249 Aconitase (aconitate hydratase; 4.2.1.3 from EC) is an iron-sulphur protein that contains a [4Fe-4S]-cluster and catalyses the interconversion of isocitrate and citrate via a cis-aconitate intermediate. Aconitase functions in both the TCA and glyoxylate cycles, however unlike the majority of iron-sulphur proteins that function as electron carriers, the [4Fe-4S]-cluster of aconitase reacts directly with an enzyme substrate. In eukaryotes there is a cytosolic form (cAcn) and a mitochondrial form (mAcn) of the enzyme. In bacteria there are also 2 forms, aconitase A (AcnA) and B (AcnB). Several aconitases are known to be multi-functional enzymes with a second non-catalytic, but essential function that arises when the cellular environment changes, such as when iron levels drop , . Eukaryotic cAcn and mAcn, and bacterial AcnA have the same domain organisation, consisting of three N-terminal alpha/beta/alpha domains, a linker region, followed by a C-terminal 'swivel' domain with a beta/beta/alpha structure (1-2-3-linker-4), although mAcn is small than cAcn. However, bacterial AcnB has a different organisation: it contains an N-terminal HEAT-like domain, followed by the 'swivel' domain, then the three alpha/beta/alpha domains (HEAT-4-1-2-3) . Below is a description of some of the multi-functional activities associated with different aconitases. Eukaryotic mAcn catalyses the second step of the mitochondrial TCA cycle, which is important for energy production, providing high energy electrons in the form of NADH and FADH2 to the mitochondrial oxidative phosphorylation pathway . The TCA cycle also provides precursors for haem and amino acid production. This enzyme has a second, non-catalytic but essential role in mitochondrial DNA (mtDNA) maintenance: mAcn acts to stabilise mtDNA, forming part of mtDNA protein-DNA complexes known as nucleoids. mAcn is thought to reversibly model nucleoids to directly influence mitochondrial gene expression in response to changes in the cellular environment. Therefore, mAcn can influence the expression of components of the oxidative phosphorylation pathway encoded in mtDNA. Eukaryotic cAcn enzyme balances the amount of citrate and isocitrate in the cytoplasm, which in turn creates a balance between the amount of NADPH generated from isocitrate by isocitrate dehydrogenase with the amount of acetyl-CoA generated from citrate by citrate lyase. Fatty acid synthesis requires both NADPH and acetyl-CoA, as do other metabolic processes, including the need for NADPH to combat oxidative stress. The enzymatic form of cAcn predominates when iron levels are normal, but if they drop sufficiently to cause the disassembly of the [4Fe-4S]-cluster, then cAcn undergoes a conformational change from a compact enzyme to a more open L-shaped protein known as iron regulatory protein 1 (IRP1; or IRE-binding protein 1, IREBP1) , . As IRP1, the catalytic site and the [4Fe-4S]-cluster are lost, and two new RNA-binding sites appear. IRP1 functions in the post-transcriptional regulation of genes involved in iron metabolism - it binds to mRNA iron-responsive elements (IRE), 30-nucleotide stem-loop structures at the 3' or 5' end of specific transcripts. Transcripts containing an IRE include ferritin L and H subunits (iron storage), transferrin (iron plasma chaperone), transferrin receptor (iron uptake into cells), ferroportin (iron exporter), mAcn, succinate dehydrogenase, erythroid aminolevulinic acid synthetase (tetrapyrrole biosynthesis), among others. If the IRE is in the 5'-UTR of the transcript (e.g. in ferritin mRNA), then IRP1-binding prevents its translation by blocking the transcript from binding to the ribosome. If the IRE is in the 3'-UTR of the transcript (e.g. transferrin receptor), then IRP1-binding protects it from endonuclease degradation, thereby prolonging the half-life of the transcript and enabling it to be translated . IRP2 is another IRE-binding protein that binds to the same transcripts as IRP1. However, since IRP1 is predominantly in the enzymatic cAcn form, it is IRP2 that acts as the major metabolic regulator that maintains iron homeostasis . Although IRP2 is homologous to IRP1, IPR2 lacks aconitase activity, and is known only to have a single function in the post-transcriptional regulation of iron metabolism genes . In iron-replete cells, IRP2 activity is regulated primarily by iron-dependent degradation through the ubiquitin-proteasomal system. Bacterial AcnB is also known to be multi-functional. In addition to its role in the TCA cycle, AcnB was shown to be a post-transcriptional regulator of gene expression in Escherichia coli and Salmonella enterica , . In S.enterica, AcnB initiates a regulatory cascade controlling flagella biosynthesis through an interaction with the ftsH transcript, an alternative RNA polymerase sigma factor. This binding lowers the intracellular concentration of FtsH protease, which in turn enhances the amount of RNA polymerase sigma32 factor (normally degraded by FtsH protease), and sigma32 then increases the synthesis of chaperone DnaK, which in turn promotes the synthesis of the flagellar protein FliC. AcnB regulates the synthesis of other proteins as well, such as superoxide dismutase (SodA) and other enzymes involved in oxidative stress. This entry represents bacterial aconitase A (AcnA), eukaryotic cytosolic aconitase (cAcn/IRP1), iron regulatory protein 2 (IRP2), and a few mitochondrial aconitases (certain mAcn proteins, but not the majority of these enzymes). More information about these proteins can be found at Protein of the Month: Aconitase .; GO: 0051539 4 iron 4 sulfur cluster binding, 0008152 metabolic process.

Probab=100.00 E-value=0 Score=3168.18 Aligned_cols=874 Identities=60% Similarity=1.005 Sum_probs=850.2 Q ss_pred EEEEEEEHHHHHHCCCCCHHHCCCHHHHHHHHHHHHCCCCCCCHHHHHHHHHCCCCCCCCCCCCCCCCCHHHEECCCCHH Q ss_conf 37998766878651577854457119999998874048665799999998612355457776636453252200000357 Q gi|254780451|r 19 IDYVYYSLPKAEANGLQGISRLPCSMKVLLENLLRFEDGCTVTKEQIHAFVKWLDNKGTVESEVSYRFSRVLMQDFTGVP 98 (896) Q Consensus 19 ~~~~~~~l~~~~~~~~~~~~~lP~s~rillEn~~R~~~~~~~~~~~~~~~~~w~~~~~~~~~ei~f~p~Rv~~qD~Tg~p 98 (896) T Consensus 1 k~~~YYsL~~l~~~G~~ki~~LPySiriLLEs~~Rn~DG~~i~~eD~e~i~~W~~~-~~~d~Ei~FkP~RV~mQDFTGVP 79 (896) T TIGR01341 1 KTYYYYSLKALEESGGGKISKLPYSIRILLESVLRNLDGFSIKEEDVEAILKWKKE-ELKDVEIAFKPARVVMQDFTGVP 79 (896) T ss_pred CCCCCCCHHHHHHCCCCCCCCCCHHHHHHHHHHHHHCCCCCCCHHHHHHHHCCCCC-CCCCCCCCCCCCEEEEECCCCCC T ss_conf 97355770899846886500041479999999987638842067899888443113-54661467564136752437872 Q ss_pred HHHHHHHHHHHHHHCCCCHHHCCCCCCEEEEEECCCHHHCCCCHHHHHHHHHHHHHHHHHHHHHHHHHHHHCCCEEEECC Q ss_conf 99999999999997199999928789813998683211005998899989998875426789999877421488078608 Q gi|254780451|r 99 AVVDLAAMRDAIVVLGGDPQNINPLVPVDLVIDHSLIVDYSGNKDAVTRNKDLEYQRNEERYRFLKWGQKSFKNFRVVPP 178 (896) Q Consensus 99 a~vdlaamR~~~~~~g~dp~~inp~vp~dlviDHsv~vd~~g~~~a~~~n~~~e~~rN~Ery~Flkwa~~~f~~~~v~pP 178 (896) T Consensus 80 AVVDLA~mR~am~~LGgDp~kINP~vPVDLVIDHSVQVD~~G~~~Ale~N~~LEFeRN~ERY~FLKWa~~AF~N~~vVPP 159 (896) T TIGR01341 80 AVVDLAAMRDAMKNLGGDPEKINPLVPVDLVIDHSVQVDYYGTEEALEKNMELEFERNLERYKFLKWAKKAFKNFKVVPP 159 (896) T ss_pred HHHHHHHHHHHHHHHCCCCCCCCCCCCCCEEECCCEEECCCCCHHHHHHHHHHHHHCCHHHHHHHHHHHHHHCCCEECCC T ss_conf 78888999999998278812048876523377560675456886799997787521044677766778875314674159 Q ss_pred CCCCHHHHHHHHHCCCEEEECCCCCEEEEEEEEEECCCCCCCCCCCHHHHCCCCHHHHHHHHCCCCCEECCCCEEEEEEE Q ss_conf 87621677898633511310368861798301320688764445201232034348999997077514116728999997 Q gi|254780451|r 179 GTGICHQINLEYLGQSVWTKNENGENIAYPDTCVGTDSHTTMINALGILGWGVGGIEAEAAMLGCPISMLLPEVVGFEVT 258 (896) Q Consensus 179 G~GI~HQvnlE~la~vv~~~~~~~~~~a~PdtlVGtDSHT~~~galG~la~GVGg~eaea~mlGqp~~~~vPevigv~L~ 258 (896) T Consensus 160 GtGI~HQVNLEYLa~VV~~~~~dG~~~aYPD~lVGTDSHTTMInGlGVLGWGVGGIEAEA~mLGqP~~~~~PeViG~kL~ 239 (896) T TIGR01341 160 GTGIVHQVNLEYLAKVVFEAEKDGELVAYPDSLVGTDSHTTMINGLGVLGWGVGGIEAEAAMLGQPVSMVVPEVIGVKLT 239 (896) T ss_pred CCCCEEECCHHHHHHHHHHHHCCCCEEECCCEEEECCCCHHHHCCCEEECCCCCHHHHHHHHCCCCEEEECCCEEEEEEE T ss_conf 88516401357889999875228846643652684686310024505612365468888886188628745866777877 Q ss_pred CCCCCCCCHHHHHHHHHHHHCCCCCCCEEEEEEECCCCCCCHHHHHHHHCCCCCCCCCEEEECCCHHHHHHHHHCCCCHH Q ss_conf 67786443688999999984102212127999615500178756321200010037203775199899999986399988 Q gi|254780451|r 259 GSLQEGVTATDLVLTITQMLRKEGVVSKFVEFFGSGFESMVLADRATIANMAPEYGATCGFFPVDRGTIDYLRLSGRSNS 338 (896) Q Consensus 259 G~L~~gVtakDiiL~i~~~Lr~~Gvvgk~vEf~G~gi~~LS~~dRaTIaNMa~E~GAt~gifp~De~T~~YL~~tGR~~~ 338 (896) T Consensus 240 GKl~~G~TATDlVL~VTqmLRK~gVVgKFVEFfGpg~~~LslaDRATIANM~PEYGATcgfFPiD~~TL~YLrLTGR~~d 319 (896) T TIGR01341 240 GKLREGVTATDLVLTVTQMLRKKGVVGKFVEFFGPGLKELSLADRATIANMAPEYGATCGFFPIDDVTLQYLRLTGRDED 319 (896) T ss_pred EECCCCCCHHHHHHHHHHHHHHCCCCCCEEEEECCCCCCCCCCCHHHHHCCCHHHHHHCCCCCCHHHHHHHHHCCCCCCC T ss_conf 42586886211352310122113764423574067620077633010322782045542689734888877541584874 Q ss_pred HHHHHHHHHHHHHCCCCCCCCC--CCCCCEEEEEECCCCCCHHCCCCCCCCEEEHHHHHHHHHHH--HHHHCCCHH---- Q ss_conf 9999998746410236767667--88630699998031430122656656413677730116687--664001100---- Q gi|254780451|r 339 RVDLVEAYTKVQGMWREDIDYE--KVAFTKKMKLDLGNVSPSVAGPRRPESRLSLSEVPSSFVTE--MNEYYKKSH---- 410 (896) Q Consensus 339 ~v~lve~Y~ka~~l~~~~~~d~--~a~Y~~vieiDLs~ieP~VAgP~~P~d~v~l~~v~~~~~~~--~~~~~~~~~---- 410 (896) T Consensus 320 ~v~~vekY~~aqglF~~P~s~~eskp~yt~~~ElDLs~vEp~~aGPKrPqdR~~L~~v~~~F~~~neL~~~~G~~~f~l~ 399 (896) T TIGR01341 320 HVDLVEKYLRAQGLFYDPDSEEESKPKYTDVVELDLSDVEPSVAGPKRPQDRVPLKEVKASFKSSNELESNAGDKGFALR 399 (896) T ss_pred HHHHHHHHHHHCCCCCCCCCCCCCCCEEEEEEEEECCCCCCCCCCCCCCCCCCCHHHHHHHHHHHHHHCCCCCCCCCCCC T ss_conf 13886898996656268888745771020188863123550237867853257868878988755210146765442114 Q ss_pred -----HHHHH----CCCCCCCCCCCCCCEEEEEEECCCCCCCHHHHHHHHHHHHHHHHCCCCCCCCCEEEEECCCHHHHH Q ss_conf -----23210----245788888755544575310467654599987788999889864987586730797016189999 Q gi|254780451|r 411 -----TLDEK----YPVKGCDFHLKHGDVAIASITSCTNTFNPSVMIGAGLLARNAVRAGLKSKPWVKTSCAPGSQVSYE 481 (896) Q Consensus 411 -----~~~~~----~~~~~~~~~l~~g~VvIAaIgSCTNtSnp~~miaAgllAkkAv~~Glkv~p~Vkt~l~PGS~~V~~ 481 (896) T Consensus 400 aeeenK~~~~k~~nfnfnG~~~~l~dGavVIAAITSCTNTSNP~VmlgAGLlAKKAVelGLkV~P~vKTSLAPGS~VVt~ 479 (896) T TIGR01341 400 AEEENKEPKEKKLNFNFNGKELQLKDGAVVIAAITSCTNTSNPSVMLGAGLLAKKAVELGLKVPPYVKTSLAPGSKVVTD 479 (896) T ss_pred CHHHCCCHHHHEEEECCCCCEEEECCCCEEEEEECCCCCCCCHHHHHHHHHHHHHHHHCCCCCCCEEEEECCCCCHHHHH T ss_conf 42212431252022001784015347888997202687775267999999888888515883188146740878635898 Q ss_pred HHHHCCCHHHHHHHCCEECCCCCCCCCCCCCCCCCHHHHHCCCCCEEEEEEECCCCCCCCCCCCCCCCEEECCHHHHHHH Q ss_conf 99985885777750530205532242127776883022101136635878633676666546854331000597899999 Q gi|254780451|r 482 YLVQAGLVEYLEALGFSLVGFGCTTCIGNSGALKKEISEVIHQKSLVVAGVLSGNRNFEGRISPDVEANYLLSPPLVVAY 561 (896) Q Consensus 482 ~L~~~Gll~~L~~aGf~i~~~GCg~CiGnsG~l~~~i~~~i~~~~l~~~sV~SgNRNFeGR~~p~~~~~yLaSP~lVvA~ 561 (896) T Consensus 480 YL~~sGLlpYL~~LGF~lVGYGCTTCIGNSGPL~~~~e~AI~~NdL~~~aVLSGNRNFEGRIHPLvK~NyLASPPLVVAY 559 (896) T TIGR01341 480 YLAESGLLPYLEELGFNLVGYGCTTCIGNSGPLPEEVEEAIVKNDLVVVAVLSGNRNFEGRIHPLVKANYLASPPLVVAY 559 (896) T ss_pred HHHHCCCCHHHHHCCCEEEECCCCCCCCCCCCCCHHHHHHHHHCCEEEEEEEECCCCCCCEECCCCCCCCCCCCHHHHHH T ss_conf 97430640368861972761443202068888878899896628828999831554633201600123534572579898 Q ss_pred HHHCCCCCCCCCCCCCCCCCCCCCCCCCCCCCHHHHHHHHHHHCCCCCCCCCCCCCCCCCHHHCCCCCCCCCCCCCCCCC Q ss_conf 85161222310023554888863200156888578888876415832100012233478712201557877620567433 Q gi|254780451|r 562 ALAGNVRKNLIKDPIGEDQQGSPVYLRDIWPKDSEIQSFVNKYVTCDLYKKKYSDVFKGDSSWWNIEVPESETYMWDEKS 641 (896) Q Consensus 562 AiaG~I~~d~~~dplg~~~~G~~v~L~DiwPs~~Ei~~~~~~~v~~~~f~~~y~~i~~g~~~w~~l~~~~~~~y~w~~~S 641 (896) T Consensus 560 ALAG~~~Inl~~~PIG~d~~Gk~VYl~DIWPS~~EI~~~V~~~V~pemF~k~Y~~~~~gN~~Wn~i~~~~~~~Y~WD~kS 639 (896) T TIGR01341 560 ALAGNVDINLETDPIGTDKDGKPVYLKDIWPSNKEIAEVVNKAVKPEMFKKEYEEVTEGNERWNKIEVTSSDLYEWDEKS 639 (896) T ss_pred HHCCCEEECCCCCCEEECCCCCEEEEECCCCCHHHHHHHHHHHCCHHHHHHHHHHHHCCHHHHCCCCCCCCCCCCCCCCC T ss_conf 51481355457787106877977886244775889999998512645678865222022033101368875554668875 Q ss_pred CCCCCCCCCCCCCCCCCCCCC--CCCCEEEEEECCCCCHHHCCCCCCCCCCCCHHHHHHHCCCCHHHHHHHHHHCCCHHH Q ss_conf 342378876776545543324--358558999658857233164565554473788898749886563145653023577 Q gi|254780451|r 642 TYVRNPPYFETISKHIPEIVD--ICGARILCLLGDKITTDHISPAGSIPLQSAAASYLRQRGVKEKDFNQFGTRRGNHEV 719 (896) Q Consensus 642 tyI~~pPff~~~~~~~~~~~~--i~~arvL~~lGD~iTTDHISPAG~I~~~spAg~yL~~~Gv~~~dfNsygsRRgNhev 719 (896) T Consensus 640 TYIr~PPfF~e~~~~P~~~~dfrikgAr~Ll~lGDSiTTDHISPAGsI~kDSPAgkYL~e~GV~r~DFNSYGSRRGNHEV 719 (896) T TIGR01341 640 TYIRNPPFFEEMKLEPEEVEDFRIKGARILLLLGDSITTDHISPAGSIKKDSPAGKYLQERGVSRRDFNSYGSRRGNHEV 719 (896) T ss_pred CCCCCCCCCCCCEECCCCCCCEEEECCEEEEECCCCEECCCCCCCCCCCCCCHHHHHHHHCCCCCCCCCCCCCCCCCCEE T ss_conf 31268484467520588889714405488874088053165688887368875788886368886515767876687424 Q ss_pred HHHHHHCCCHHHHHHCCCCCCCCCCEEECCCCCEEEHHHHHHHHHHCCCCEEEECCCCCCCCCHHHHHHHHHHHCCEEEE Q ss_conf 76652036012232125777657722453899787379999989981998899946777867307999886676170899 Q gi|254780451|r 720 MMRGTFSNIRICNYMLGEEGKKGGYTIHYPSKEELFIYDAAMRYKVDQVPLVVFAGVEYGNGSSRDWAAKGTRLLGVRSV 799 (896) Q Consensus 720 M~RGtFaNirl~N~l~~~~~~egg~T~~~p~~~~~~iydaA~~Y~~~~~plVViAG~~YG~GSSRdwAAkgp~lLGVkAV 799 (896) T Consensus 720 MmRGTFANiRIkN~~v--~G~EGG~T~h~P~~~~~SvYDAAM~YK~eg~plvv~AGKeYGsGSSRDWAAKGt~LLGvkaV 797 (896) T TIGR01341 720 MMRGTFANIRIKNLMV--KGKEGGYTVHLPDGEVLSVYDAAMKYKKEGTPLVVIAGKEYGSGSSRDWAAKGTKLLGVKAV 797 (896) T ss_pred CCCCCCCCHHEEEEEC--CCEECCEEEEECCCCCEEEHHHHHHHHCCCCCEEEEECCCCCCCCCCHHHHCCCCCCCEEEE T ss_conf 0467522600052240--66037856664188434500444341017888799942404898860466308854514799 Q ss_pred EECCHHHHHHHCCCCCEEEEEECCCCCCHHHHCCCCCE--EEEEECHHHCCCCCEEEEEEEECCCCEEEEEEEEEECCHH Q ss_conf 97647898885053552322331789898881989743--8997263225899738999981899679999998738999 Q gi|254780451|r 800 IAESFERIHRSNLIGMGVIPFAFGKGISWKNLNIKGDE--IINIRKLKTISPRQESTLEIHYSDGTFKCVPIICCIDTLD 877 (896) Q Consensus 800 IA~SFeRIHrsNLv~mGiLPL~F~~~~~~~~L~l~G~E--~~~i~~~~~l~p~~~v~v~i~~~~g~~~~~~~~~r~dt~~ 877 (896) T Consensus 798 IAeSFERIHRSNLVgMGviPl~f~~g~~a~TLGl~G~E~~~id~~~i~~~~Pg~~vtv~~~~~~G~~~t~~~~~R~Dt~v 877 (896) T TIGR01341 798 IAESFERIHRSNLVGMGVIPLEFKQGEDAETLGLTGEELITIDVDDIKEIKPGKEVTVTLTNKDGEKETFECVLRIDTEV 877 (896) T ss_pred EECCCCHHHHHHHHHHCCCCCCCCCCCCCCCCCCCCCEEEEEECCCCCCCCCCCCEEEEEECCCCCEEEEEEEEEECCHH T ss_conf 83253303323324304122105888871125787536999865886634889702589983689788997888725468 Q ss_pred HHHHHHCCCHHHHHHHHH Q ss_conf 999999098368988872 Q gi|254780451|r 878 EINHLKNGGILQAVLRQL 895 (896) Q Consensus 878 E~~~~~~GGiL~yvlr~l 895 (896) T Consensus 878 El~Y~~~GGILqYVlr~~ 895 (896) T TIGR01341 878 ELDYYKHGGILQYVLRKL 895 (896) T ss_pred HHHHHHCCCCHHHHHHHH T ss_conf 988863588315788740

HHsearch alignment for GI: 254780451 and conserved domain: TIGR01341