>TIGR01991 HscA Fe-S protein assembly chaperone HscA; InterPro: IPR010236 Iron-sulphur (FeS) clusters are important cofactors for numerous proteins involved in electron transfer, in redox and non-redox catalysis, in gene regulation, and as sensors of oxygen and iron. These functions depend on the various FeS cluster prosthetic groups, the most common being [2Fe-2S] and [4Fe-4S] . FeS cluster assembly is a complex process involving the mobilisation of Fe and S atoms from storage sources, their assembly into [Fe-S] form, their transport to specific cellular locations, and their transfer to recipient apoproteins. So far, three FeS assembly machineries have been identified, which are capable of synthesising all types of [Fe-S] clusters: ISC (iron-sulphur cluster), SUF (sulphur assimilation), and NIF (nitrogen fixation) systems. The ISC system is conserved in eubacteria and eukaryotes (mitochondria), and has broad specificity, targeting general FeS proteins , . It is encoded by the isc operon (iscRSUA-hscBA-fdx-iscX). IscS is a cysteine desulphurase, which obtains S from cysteine (converting it to alanine) and serves as a S donor for FeS cluster assembly. IscU and IscA act as scaffolds to accept S and Fe atoms, assembling clusters and transfering them to recipient apoproteins. HscA is a molecular chaperone and HscB is a co-chaperone. Fdx is a [2Fe-2S]-type ferredoxin. IscR is a transcription factor that regulates expression of the isc operon. IscX (also known as YfhJ) appears to interact with IscS and may function as an Fe donor during cluster assembly . The SUF system is an alternative pathway to the ISC system that operates under iron starvation and oxidative stress. It is found in eubacteria, archaea and eukaryotes (plastids). The SUF system is encoded by the suf operon (sufABCDSE), and the six encoded proteins are arranged into two complexes (SufSE and SufBCD) and one protein (SufA). SufS is a pyridoxal-phosphate (PLP) protein displaying cysteine desulphurase activity. SufE acts as a scaffold protein that accepts S from SufS and donates it to SufA . SufC is an ATPase with an unorthodox ATP-binding cassette (ABC)-like component. No specific functions have been assigned to SufB and SufD. SufA is homologous to IscA , acting as a scaffold protein in which Fe and S atoms are assembled into [FeS] cluster forms, which can then easily be transferred to apoproteins targets. In the NIF system, NifS and NifU are required for the formation of metalloclusters of nitrogenase in Azotobacter vinelandii, and other organisms, as well as in the maturation of other FeS proteins. Nitrogenase catalyses the fixation of nitrogen. It contains a complex cluster, the FeMo cofactor, which contains molybdenum, Fe and S. NifS is a cysteine desulphurase. NifU binds one Fe atom at its N-terminal, assembling an FeS cluster that is transferred to nitrogenase apoproteins . Nif proteins involved in the formation of FeS clusters can also be found in organisms that do not fix nitrogen . This entry represents the HscA chaperone protein from the SUF system. HscA (or Hsc66) is a specialised bacterial Hsp70-class molecular chaperone that participates in the assembly of iron-sulphur cluster proteins. HscA resembles DnaK, but belongs to a separate clade. HscA interacts with IscU, which is believed to serve as a template for Fe-S cluster formation. The HscA-IscU interaction is facilitated by the J-type co-chaperone protein HscB (or Hsc20), which binds to both HscA and IscU, bringing them into contact with each other. HscA recognises a conserved LPPVK sequence motif at positions 99-103 of IscU .; GO: 0005524 ATP binding, 0016887 ATPase activity, 0051082 unfolded protein binding, 0016226 iron-sulfur cluster assembly.

Probab=99.84 E-value=9e-20 Score=135.77 Aligned_cols=327 Identities=21% Similarity=0.321 Sum_probs=203.5 Q ss_pred CEEEEEEECCCEEEEEEEEECCCCCCCCCCCCCCCEEEEEEEECCCCC-CCCCE------EECHHHHHHHHHHHHHHHHH Q ss_conf 679999914980699999833766533335677615999996110111-00883------74789999999999999999 Q gi|254781177|r 22 YIVSALDIGSTKTVCMIGKLVPQNTTSLLSGRTHRIEVIGIGCQQSHG-VKMGT------IVDIDAVERVVRQVVDAAER 94 (440) Q Consensus 22 ~ii~~iDiGsski~~~v~e~~~~~~~~~~~~~~~~~~iig~g~~~s~g-i~~G~------I~d~~~~~~~I~~ai~~ae~ 94 (440) T Consensus 23 rla~GIDLGTTnS--LVA~vrseg~a~~lpd~eGr~~lPSvV~Y~~~gG~~VG~~Ar~~a~~dp~nTv~S~KRlm----- 95 (628) T TIGR01991 23 RLAVGIDLGTTNS--LVAAVRSEGKAECLPDAEGRLLLPSVVRYLADGGVEVGKAAREAAASDPLNTVISVKRLM----- 95 (628) T ss_pred CEEEEECCCCCCC--CEEEEECCCCCCCCCCCCCCEECCCEEEECCCCCCHHHHHHHHHHHHCCCHHHHHHHHHH----- T ss_conf 3776211453210--102330475988776768676546225761468802668999997527700345626651----- Q ss_pred HHCCEEEEEEEE---CCCCCCCCEEEEEEECCC----CC-CCCHHHHHHHHHHHHHHHCCCCCEEEEEEECCEEEECCCC Q ss_conf 829765379997---268766403211120354----10-0352789999986423214865324577511211556865 Q gi|254781177|r 95 MAGFTVDNLLVN---ISAGCLKSQQHFVEMKIG----WR-EVNDSDIQILLKSSFRRYLRDQKRTLLHSIITDYALDGKS 166 (440) Q Consensus 95 ~ag~~i~~v~v~---i~g~~i~s~~~~~~~~~~----~~-~I~~~DI~~~i~~a~~~~~~~~~~~iih~~p~~y~iD~~~ 166 (440) T Consensus 96 --GR~L~Dv~q~~~~lPYrf~~~e~g~~~~~T~~G~~~PVeV-SA~IL~~L~~rAe~~LgG------------------- 153 (628) T TIGR01991 96 --GRGLEDVQQEGKRLPYRFEAGESGMVEIETAQGLKSPVEV-SAEILKELKARAEEALGG------------------- 153 (628) T ss_pred --CCCHHHHCCCCCCCCCCCCCCCCCCEEEECCCCCCCCHHH-HHHHHHHHHHHHHHHHCC------------------- T ss_conf --5765765256577870001588985477335675263134-378999999988663055------------------- Q ss_pred CCCCCCCCCCCEEEEEEEEEECCH---HHHHH-HHHHHHHCCCCCCCCCCCHHHHHHHHCCCCCCCCCEEEE-EECCCCE Q ss_conf 566722342320368999972313---68888-998765323311233321023455312433455507999-9537715 Q gi|254781177|r 167 GIKSPISMFADKIGIESHLLTVEK---SSMKN-LERAINRAHLSVERMVASPYASGLATLVDDEFELGSVVI-DMGGGTT 241 (440) Q Consensus 167 ~v~nPiGm~g~~L~v~~~~v~~~~---~~i~~-~~~~i~~~gl~v~~i~~~p~Asa~a~L~~~ek~~Gv~iI-DiGa~tT 241 (440) T Consensus 154 -------------~L~G~VITVPAYFDDAQRQaTKDAaRLAGL~VLRLlNEPTAAA~AYGLd~g-~EG~~avYDLGGGTF 219 (628) T TIGR01991 154 -------------ELVGVVITVPAYFDDAQRQATKDAARLAGLNVLRLLNEPTAAAIAYGLDKG-KEGLVAVYDLGGGTF 219 (628) T ss_pred -------------CCCEEEEEECCCCCHHHHHHHHHHHHHHHHHHHHHCCHHHHHHHHHCCCCC-CCCEEEEEECCCCHH T ss_conf -------------401168970675540221201578876235777641614799998311278-876499983788710 Q ss_pred EEEEEECCCCEEEEEEC------CCHHHHHHHHHHHC----CCCH---HHHHHHHHHCCCC-CCCCCCCHHCCCCCCCCC Q ss_conf 57884035302453102------42277508888633----4523---6788876425740-335553000012233578 Q gi|254781177|r 242 KIAIFDKGKLVYMDVIA------IGGSHVTNDLARGL----SISL---DNAERLKVMHPSI-IPSLADEHDILSIPTIGN 307 (440) Q Consensus 242 ~i~i~~~g~l~~~~~i~------iGG~~iT~DIa~~l----~i~~---~eAE~lK~~~G~a-~~~~~~~~~~i~~~~~~~ 307 (440) T Consensus 220 DiSiL~L~kGvF-eV~aTGGdsALGGDDFDH~l~~~~~eq~G~~~~~~~~~q~~lL~~a~aAKe~Ltd-~~~v~v~~~~~ 297 (628) T TIGR01991 220 DISILRLSKGVF-EVLATGGDSALGGDDFDHALADLLLEQAGLSQDLDEEQQRQLLSLARAAKEALTD-AESVRVAVGDW 297 (628) T ss_pred HHHHHHHCCCCE-EEEECCCCCCCCCCCHHHHHHHHHHHHCCCCCCCCHHHHHHHHHHHHHHHHHCCC-CCEEEEEEECC T ss_conf 355643403203-6530477856677637789999999865897677836789999999999864486-33468888515 Q ss_pred CCCCCEEECCHHHHHHHHHHHHHHHHHHHHHHHHHCCCCCCCCCEEEEECCCCCCCCHHHHHHHHHCCCEEEECCCCCCC Q ss_conf 87653043389999999999999999988887640686445774399973234445789999998389759971433478 Q gi|254781177|r 308 ADHNDLVQVSRAMISRIIQARIEETFELIGERIKKSGFSSLASKRIVLTGGASQVIGLQEMLRETICSNVRMGRPIGAVG 387 (440) Q Consensus 308 ~~~~~~~~i~~~~l~~II~~Rv~ei~~~i~~~l~~~~~~~~~~~~IvLtGGgs~l~gl~~~~~~~~~~~vri~~P~~~~g 387 (440) T Consensus 298 ~g~aidt~lSra~f~~li~~LV~rtl~~crrAlkDaGV~~~e~~~VvmVGGSTRvp~Vr~~VaelFg~~-----PL--~~ 370 (628) T TIGR01991 298 DGEAIDTELSRAEFEELIEPLVKRTLLPCRRALKDAGVEKEEVKGVVMVGGSTRVPKVREAVAELFGRE-----PL--TD 370 (628) T ss_pred CCCCHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHCCCCHHHCCEEEEECCCCCHHHHHHHHHHHHCCC-----CC--CC T ss_conf 770201565289998899999985216788888752788325326578626546167999998863778-----78--88 Q ss_pred CHHHHCCCHHHHHHHHHH Q ss_conf 212223723799999999 Q gi|254781177|r 388 LPFSARSPAFSTVIGLMI 405 (440) Q Consensus 388 ~~~~~~~p~~sta~Gl~~ 405 (440) T Consensus 371 -----ldPD~VVAlGAAi 383 (628) T TIGR01991 371 -----LDPDKVVALGAAI 383 (628) T ss_pred -----CCCCHHHHHHHHH T ss_conf -----8751424655899

HHsearch alignment for GI: 254781177 and conserved domain: TIGR01991