>TIGR02769 nickel_nikE nickel import ATP-binding protein NikE; InterPro: IPR014137 ABC transporters belong to the ATP-Binding Cassette (ABC) superfamily, which uses the hydrolysis of ATP to energize diverse biological systems. ABC transporters are minimally constituted of two conserved regions: a highly conserved ATP binding cassette (ABC) and a less conserved transmembrane domain (TMD). These regions can be found on the same protein or on two different ones. Most ABC transporters function as a dimer and therefore are constituted of four domains, two ABC modules and two TMDs. ABC transporters are involved in the export or import of a wide variety of substrates ranging from small ions to macromolecules. The major function of ABC import systems is to provide essential nutrients to bacteria. They are found only in prokaryotes and their four constitutive domains are usually encoded by independent polypeptides (two ABC proteins and two TMD proteins). Prokaryotic importers require additional extracytoplasmic binding proteins (one or more per systems) for function. In contrast, export systems are involved in the extrusion of noxious substances, the export of extracellular toxins and the targeting of membrane components. They are found in all living organisms and in general the TMD is fused to the ABC module in a variety of combinations. Some eukaryotic exporters encode the four domains on the same polypeptide chain . The ABC module (approximately two hundred amino acid residues) is known to bind and hydrolyze ATP, thereby coupling transport to ATP hydrolysis in a large number of biological processes. The cassette is duplicated in several subfamilies. Its primary sequence is highly conserved, displaying a typical phosphate-binding loop: Walker A, and a magnesium binding site: Walker B. Besides these two regions, three other conserved motifs are present in the ABC cassette: the switch region which contains a histidine loop, postulated to polarize the attaching water molecule for hydrolysis, the signature conserved motif (LSGGQ) specific to the ABC transporter, and the Q-motif (between Walker A and the signature), which interacts with the gamma phosphate through a water bond. The Walker A, Walker B, Q-loop and switch region form the nucleotide binding site , , . The 3D structure of a monomeric ABC module adopts a stubby L-shape with two distinct arms. ArmI (mainly beta-strand) contains Walker A and Walker B. The important residues for ATP hydrolysis and/or binding are located in the P-loop. The ATP-binding pocket is located at the extremity of armI. The perpendicular armII contains mostly the alpha helical subdomain with the signature motif. It only seems to be required for structural integrity of the ABC module. ArmII is in direct contact with the TMD. The hinge between armI and armII contains both the histidine loop and the Q-loop, making contact with the gamma phosphate of the ATP molecule. ATP hydrolysis leads to a conformational change that could facilitate ADP release. In the dimer the two ABC cassettes contact each other through hydrophobic interactions at the antiparallel beta-sheet of armI by a two-fold axis , , , , , . Proteins known to belong to this family are classified in several functional subfamilies depending on the substrate used (for further information see http://www.tcdb.org/tcdb/index.php?tc=3.A.1). This family represents the NikE subunit of a multisubunit nickel import ABC transporter complex. Nickel, once imported, may be used in urease and in certain classes of hydrogenase and superoxide dismutase..

Probab=95.79  E-value=0.017  Score=34.98  Aligned_cols=150  Identities=21%  Similarity=0.262  Sum_probs=86.6

Q ss_pred             EEEEEEEEECEEEEECCCCCCCEEEEEECC-CCCHHHH-----HHHCCCEECCEEEEECCEEEEEECCCCCCCCCCCCCC
Q ss_conf             999997630112442167775303541014-5401212-----1100000010266329868998226421247311677
Q gi|254780648|r  152 IWLKLKLIADIGIIGLPNAGKSTFLASVTR-AKPKIAD-----YPFTTLYPNLGIVKEGYKEFILADIPGIIKNAHQGAG  225 (335)
Q Consensus       152 ~~lelk~iaDVglVG~PNaGKSTLln~ls~-ak~kIa~-----ypFTT~~P~lGvv~~~~~~~~i~D~PGlIegA~~~~g  225 (335)
T Consensus        31 vsL~l~~Ge~~gLLG~SG~GKSTLArlLlGLe~P~~G~v~F~G~dl~~L~~~~~rafrR~vQlvFQD~~savN-Pr~tv~  109 (267)
T TIGR02769        31 VSLSLEEGETVGLLGRSGCGKSTLARLLLGLEKPAQGEVSFRGQDLSKLDRKQRRAFRRDVQLVFQDSPSAVN-PRKTVR  109 (267)
T ss_pred             CCEEECCCCEEEECCCCCCCHHHHHHHHHHCCCCCCCEEEECCCCHHHCCHHHCCEEEEEEEEEEECCCCCCC-HHHHHH
T ss_conf             4323137750552367887377899998750788874047625645550811021112136789874743116-257899


Q ss_pred             --CHHHHHHHHHH---------HHHHHHHCCCCCCC----HHH----HHHHHHHHHHHHHHHHCCCCEEEEE----ECCC
Q ss_conf             --51234433333---------57887520222211----013----4666789987776675059889999----7465
Q gi|254780648|r  226 --IGDRFLKHTER---------THVLLHIVSALEEN----VQA----AYQCILDELSAYNSELRKKIEIVGL----SQID  282 (335)
Q Consensus       226 --lG~~FLrhIer---------~~vLl~VVD~s~~d----~~~----~~~~I~~EL~~y~~~L~~Kp~IIVl----NKiD  282 (335)
T Consensus       110 ~ii~-EPLrhl~~L~~s~~~~r~~~LL~~v~L~~~~~~k~P~qlSGGQLQRin--i---ARALA~~PkLivLDEavSnLD  183 (267)
T TIGR02769       110 EIIG-EPLRHLTSLDESERKARIAELLELVGLRSEVADKLPRQLSGGQLQRIN--I---ARALAVKPKLIVLDEAVSNLD  183 (267)
T ss_pred             HHHH-HHHHHHHHHHHHHHHHHHHHHHHHCCCCHHHHHCCCCCCCCCHHHHHH--H---HHHHHCCCCEEEEHHHHHHHH
T ss_conf             9986-257766548899999999999986088967984287000574689999--9---999730897375322255767


Q ss_pred             CCCHHHHHHHHHHHHHHCCCCEEEEE
Q ss_conf             89988999999999986299489998
Q gi|254780648|r  283 TVDSDTLARKKNELATQCGQVPFEFS  308 (335)
Q Consensus       283 l~~~e~~~~~~~~l~~~~~~~vi~IS  308 (335)
T Consensus       184 ~~lQ~~iL~lL~~L~q~~G~aylfit  209 (267)
T TIGR02769       184 LVLQAVILELLKKLQQEFGTAYLFIT  209 (267)
T ss_pred             HHHHHHHHHHHHHHHHHHCCEEEHHH
T ss_conf             99999999999999870095541356