View source for 2awn

==Crystal structure of the ADP-Mg-bound E. Coli MALK (Crystallized with ATP-Mg)==
<StructureSection load='2awn' size='340' side='right' caption='[[2awn]], [[Resolution|resolution]] 2.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2awn]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2AWN OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2AWN FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ADP:ADENOSINE-5-DIPHOSPHATE'>ADP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1q12|1q12]], [[1q1b|1q1b]], [[1q1e|1q1e]]</td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">malK ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])</td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Maltose-transporting_ATPase Maltose-transporting ATPase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.6.3.19 3.6.3.19] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2awn FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2awn OCA], [http://www.rcsb.org/pdb/explore.do?structureId=2awn RCSB], [http://www.ebi.ac.uk/pdbsum/2awn PDBsum]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/MALK_ECOLI MALK_ECOLI]] Part of the ABC transporter complex MalEFGK involved in maltose/maltodextrin import. Responsible for energy coupling to the transport system. 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/aw/2awn_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
ATP-binding cassette (ABC) transporters couple ATP binding and hydrolysis to the movement of substances across the membrane; conformational changes clearly play an important role in the transporter mechanism. Previously, we have shown that a dimer of MalK, the ATPase subunit of the maltose transporter from Escherichia coli, undergoes a tweezers-like motion in a transport cycle. The MalK monomer consists of an N-terminal nucleotide binding domain and a C-terminal regulatory domain. The two nucleotide-binding domains in a dimer are either open or closed, depending on whether ATP is present, while the regulatory domains maintain contacts to hold the dimer together. In this work, the structure of MalK in a posthydrolysis state is presented, obtained by cocrystallizing MalK with ATP-Mg(2+). ATP was hydrolyzed in the crystallization drop, and ADP-Mg(2+) was found in the resulting crystal structure. In contrast to the ATP-bound form where two ATP molecules are buried in a closed interface between the nucleotide-binding domains, the two nucleotide-binding domains of the ADP-bound form are open, indicating that ADP, unlike ATP, cannot stabilize the closed form. This conclusion is further supported by oligomerization studies of MalK in solution. At low protein concentrations, ATP promotes dimerization of MalK, whereas ADP does not. The structures of dimeric MalK in the nucleotide-free, ATP-bound, and ADP-bound forms provide a framework for understanding the nature of the conformational changes that occur in an ATP-binding cassette transporter hydrolysis cycle, as well as how conformational changes in MalK are coupled to solute transport.

ATP hydrolysis is required to reset the ATP-binding cassette dimer into the resting-state conformation.,Lu G, Westbrooks JM, Davidson AL, Chen J Proc Natl Acad Sci U S A. 2005 Dec 13;102(50):17969-74. Epub 2005 Dec 2. PMID:16326809<ref>PMID:16326809</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Maltose-transporting ATPase]]
[[Category: Chen, J]]
[[Category: Davidson, A L]]
[[Category: Lu, G]]
[[Category: Westbrooks, J M]]
[[Category: Atp-binding cassette]]
[[Category: Transport protein]]