>TIGR03004 ectoine_ehuC ectoine/hydroxyectoine ABC transporter, permease protein EhuC; InterPro: IPR014342 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). Members of this entry are presumed to act as permease subunits of ectoine ABC transporters. Operons containing this gene also contain other genes of the ABC transporter and are typically found next to either ectoine utilization or ectoine biosynthesis operons. Permease subunits EhuC and EhuD are homologues..

Probab=99.43  E-value=1.1e-11  Score=88.85  Aligned_cols=192  Identities=19%  Similarity=0.277  Sum_probs=152.9

Q ss_pred             CHHHHHHHHHHHHHHHHHHHHHHHHHHHH-CCCCHHHHHCCCHHHHHHHHCCCCC---HHHHHHHH--CCCCHHH---HH
Q ss_conf             44999999999999997887666776421-0121123202350345442012021---01100000--0210178---89
Q gi|254780341|r   89 YWQETTETLSLVLVSTFISMFIGVPLGVL-AAWYPRFYSIIRLFLDSMQTIPTFV---YLIPALVL--FGLGMVP---GI  159 (281)
Q Consensus        89 ~W~~~~~Tl~~~~~~~~ia~~igiplGi~-~~~~~~~~~~~~p~l~~~~~iP~~v---~l~p~i~~--fG~g~~~---~i  159 (281)
T Consensus         7 ~lQGAwVT~~iTl~gs~la~V~Af~aglgr~s~~~~lr~~a~~YiE~FRGTSllVQLFW~yfvLPlPP~gl~l~P~t~gv   86 (216)
T TIGR03004         7 LLQGAWVTLQITLAGSVLAVVVAFLAGLGRLSRFRILRALAVVYIEVFRGTSLLVQLFWLYFVLPLPPIGLELDPLTVGV   86 (216)
T ss_pred             HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHCCCHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHCCCCCCCCCCHHHHHH
T ss_conf             99889999999999999999999999887523535887777787544203789999999999725799984025189999


Q ss_pred             HHHHHHHHHHHHHHHHHHHHCCCHHHHHHHHHCCCCHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHCCCCHH
Q ss_conf             99999887899999588741299899999996078820101223688626799999999999999999999997058804
Q gi|254780341|r  160 VATIVFSIPTSVRLTRLGIISTPPILKEAACAFGATPFQVFRKVELPFAIPQIVASLTQTIMLSLSMVVVTALVGSNGLG  239 (281)
Q Consensus       160 ~a~~i~~~~pi~~~t~~gl~~v~~~~~eaa~~~Gas~~q~l~~V~lP~a~P~i~~Gi~~~~~~~l~~vvia~~ig~~GLG  239 (281)
T Consensus        87 ~~Lglh~GaYGAEivRGA~~sv~~~Q~EAc~ALNftrfq~~rrI~LPQAl~~mmp~fgNlaIElLK~tslVSLIslaDlt  166 (216)
T TIGR03004        87 LALGLHVGAYGAEIVRGAVKSVSKEQLEACIALNFTRFQALRRIVLPQALVEMMPAFGNLAIELLKLTSLVSLISLADLT  166 (216)
T ss_pred             HHHHHHCCCCHHHHHHHHHHHHHHHHHHHHHHHCCHHHHHHHHHHHHHHHHHHCCCCCHHHHHHHHHHHHHHHHHHHHHH
T ss_conf             99997326501688888899743658999998415367799876326799974386615899999878999999998676


Q ss_pred             HHHHHH-HHHHCHHHHHHHHHHH-HHHHHHHHHHHHHHHHHCC
Q ss_conf             999999-9740789899999999-9999999999998742105
Q gi|254780341|r  240 VPVLRA-LNTVDIGRGFESGLCI-VILAIILDRLFSIPDPRDR  280 (281)
Q Consensus       240 ~~i~~a-~~~~~~~~~~~~~l~I-v~lai~lDri~~~~~~r~~  280 (281)
T Consensus       167 F~Aq~~r~~T~~tl~~fa~~LL~YFvMa~~i~l~~R~lEr~v~  209 (216)
T TIGR03004       167 FRAQSVRALTLDTLKVFALILLLYFVMALIISLAMRVLERRVA  209 (216)
T ss_pred             HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHC
T ss_conf             9999999841002799999999999999999999998866640