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2awo

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[[Image:2awo.gif|left|200px]]
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{{STRUCTURE_2awo| PDB=2awo | SCENE= }}
{{STRUCTURE_2awo| PDB=2awo | SCENE= }}
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'''Crystal structure of the ADP-Mg-bound E. Coli MALK (Crystallized with ADP-Mg)'''
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===Crystal structure of the ADP-Mg-bound E. Coli MALK (Crystallized with ADP-Mg)===
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==Overview==
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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.
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(as it appears on PubMed at http://www.pubmed.gov), where 16326809 is the PubMed ID number.
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{{ABSTRACT_PUBMED_16326809}}
==About this Structure==
==About this Structure==
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[[Category: Westbrooks, J M.]]
[[Category: Westbrooks, J M.]]
[[Category: Atp-binding cassette]]
[[Category: Atp-binding cassette]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 19:33:49 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 06:10:51 2008''

Revision as of 03:10, 29 July 2008

Image:2awo.png

Template:STRUCTURE 2awo

Crystal structure of the ADP-Mg-bound E. Coli MALK (Crystallized with ADP-Mg)

Template:ABSTRACT PUBMED 16326809

About this Structure

2AWO is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

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

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