>TIGR02011 IscA iron-sulfur cluster assembly protein IscA; InterPro: IPR011302 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 IscA component of the ISC system for iron-sulphur cluster assembly. IscA is believed to act as a scaffold upon which 2Fe-2S clusters are assembled and subsequently transferred to ferredoxin , , . This clade is limited to the proteobacteria.; GO: 0005506 iron ion binding, 0005515 protein binding, 0051536 iron-sulfur cluster binding, 0016226 iron-sulfur cluster assembly.

Probab=99.96  E-value=3.4e-29  Score=191.89  Aligned_cols=105  Identities=38%  Similarity=0.805  Sum_probs=103.1

Q ss_pred             EEECHHHHHHHHHHHHHCCCCCEEEEEEECCCCCCEEEEEHHHHCCCCCCCEECCCCEEEEECHHHHHHCCCCEEEEEEC
Q ss_conf             33188999999999972898847999983688765146533321035211300468789998467765406879998727
Q gi|254780287|r    5 IKITDAAATQIKTILESNSDKKALRITIEGGGCSGFSYKFDLESKQSEDDIVFEKNGAQIFIDKISLAYLTNSEIDFVDN   84 (109)
Q Consensus         5 i~iT~~A~~~i~~l~~~~~~~~~lRi~v~~gGCsG~~y~l~~~~~~~~~D~v~~~~gi~v~vd~~s~~~L~g~~IDy~~~   84 (109)
T Consensus         1 itl~~~a~~~~~~~la~rGkG~G~rlG~~tsGCsGmay~lefvd~~~~~d~~~~~~G~~~~~d~ksl~yl~G~~~d~~ke   80 (105)
T TIGR02011         1 ITLTEAAAERVNSFLANRGKGLGLRLGVKTSGCSGMAYVLEFVDEADDDDLVFEDKGVKIVIDAKSLVYLDGTQLDFVKE   80 (105)
T ss_pred             CCCCHHHHHHHHHHHHHCCCCEEEEEEEEECCCCCEEEEEEECCCCCCCCEEECCCCCEEEECCCEEEEECCCEEEEEEC
T ss_conf             94367789999998861488204674100036552000121102688885366168717898174134322622210100


Q ss_pred             CCCCEEEEECCCCCCCCCCCCCCCC
Q ss_conf             8545238988888887788622469
Q gi|254780287|r   85 LLSKSFQIRNPNATSNCGCGTSFSI  109 (109)
Q Consensus        85 ~~g~gF~i~nPna~~~CgCG~SF~~  109 (109)
T Consensus        81 Gl~eGf~f~nPn~k~~CGCGesf~v  105 (105)
T TIGR02011        81 GLNEGFKFENPNVKDECGCGESFHV  105 (105)
T ss_pred             HHHCCCEECCCCCCCCCCCCCCCCC
T ss_conf             1113731048876666677632349