HHsearch alignment for GI: 254780684 and conserved domain: TIGR02982

>TIGR02982 heterocyst_DevA ABC exporter ATP-binding subunit, DevA family; InterPro: IPR014324 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 entry represents the ATP-binding subunit DevA, found mostly in the Cyanobacteria, but also in the Planctomycetes. Cyanobacterial examples are involved in heterocyst formation, by which some fraction of members of the colony undergo a developmental change and become capable of nitrogen fixation. The ABC transporter encoded by the devBCA operon is induced by nitrogen deficiency and is necessary for the formation of the laminated layer which envelops heterocysts , . It is thought to be involved in the export of either the heterocyst-specific glycolipids found in the laminated layer, or an enzyme essential for their formation..
Probab=92.20  E-value=0.1  Score=31.51  Aligned_cols=105  Identities=17%  Similarity=0.229  Sum_probs=53.0

Q ss_pred             HHHHHHCCCCEEEEECCCCCCHHHHHHHHH--HH-CCCCCEEEEE--CCCCCHHHHHHHHHHHCCCC---CCEEEEEECC
Q ss_conf             520022358503752667889999999987--40-7898389931--24652238899998642775---5328984157
Q gi|254780684|r  153 DIFTPLCHGQRIGVFAGSGIGKSTLLSMFA--RS-DCFDKVIISL--VGERGREVREFIEDYLGDNL---KKSVVVVATS  224 (438)
Q Consensus       153 D~l~pig~GQR~gIfg~~GvGKt~Ll~~i~--~~-~~~dv~V~al--IGeR~rev~efi~~~~~~~l---~~tvvv~~t~  224 (438)
T Consensus        23 di~L~i~~GEiViltGPSGSGKTTLLtLiG~LR~~Q~G~L~vlg~~L~ga~~~~l~~~RR~---iGyIFQ~HNLl~~LTA   99 (220)
T TIGR02982        23 DINLEINPGEIVILTGPSGSGKTTLLTLIGGLRSVQEGSLKVLGQELKGASKKELVQVRRN---IGYIFQAHNLLGFLTA   99 (220)
T ss_pred             CCCEEECCCEEEEEECCCCCCHHHHHHHHHHHCCCCCCEEEEECCHHCCCCHHHHHHHHHH---CCCEECCCHHCHHHHH
T ss_conf             7631771764798437889846889998876256555604782201026788899999876---3914412000100017


Q ss_pred             CCCHHH-----HHHHHHHHHHH-HHHHHHCC--CCEEEEEECHH
Q ss_conf             788034-----44444567778-88864267--98899970989
Q gi|254780684|r  225 DESPIL-----RKMAPLTAVTI-AEYFSSKG--DNVLLILDSIT  260 (438)
Q Consensus       225 d~~~~~-----r~~a~~~a~~i-AEyfr~~G--~~Vll~~Ds~t  260 (438)
T Consensus       100 ~QNVqM~~eL~~~~~~~~~~~~a~~~L~~VGL~~~~~y~P~~LS  143 (220)
T TIGR02982       100 RQNVQMALELQPNLSAQEAREKARAMLEAVGLGDRLDYYPENLS  143 (220)
T ss_pred             HHHHHHHHHHHHHCCHHHHHHHHHHHHHHHCHHHHHHHCCCCCC
T ss_conf             78886489887611688999999999986060125540524367