ATP-binding cassette (ABC) transporters are ubiquitous transmembrane protein complexes that couple ATP binding and hydrolysis to the movement of substances across the membrane. More than a dozen human diseases have been traced to ABC proteins including cystic fibrosis, Startgardt disease and Tangier disease. Over-expression of some ABC transporters in tumor cells confers drug resistance by pumping the drugs out of the cells, a phenomenon that becomes one of the major barriers to effective treatment of cancer. We propose to study the molecular mechanism underlying the active transport process mediated by ABC proteins, using the E coli maltose transporter (MalFGK2) as a model system. Specifically, we plan to: (1) determine the crystal structures of the ATPase subunit, MalK, in different catalytic stages of the ATP hydrolysis; (2) to study biochemically and physically the mechanism underlying inducer exclusion, in which Enzyme IIAglc binds to MalK and inhibits maltose transport when glucose is present in the medium; (3) to reveal the molecular interface between MalK and the transmembrane subunits using various biochemical and physical methods; and (4) to determine the crystal structure of the entire transport complex in a transition-state-like intermediate form. At the completion of the proposed studies, we expect that we will have gained new knowledge on how the ATPase activity of the transporter is regulated, how ATPase subunits interact with the transmembrane subunits, and what happens during the maltose transport cycle. Because all members of ABC transporter family share a common domain organization and high degree of sequence similarity, the knowledge of the E. coli maltose transport mechanism will advance our understanding of how conformational changes of ABC transporters facilitate the transport processes.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM070515-03
Application #
7048670
Study Section
Physical Biochemistry Study Section (PB)
Program Officer
Chin, Jean
Project Start
2004-04-01
Project End
2009-03-31
Budget Start
2006-04-01
Budget End
2007-03-31
Support Year
3
Fiscal Year
2006
Total Cost
$277,571
Indirect Cost
Name
Purdue University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
072051394
City
West Lafayette
State
IN
Country
United States
Zip Code
47907
Bajaj, Ruchika; Park, Mariana I; Stauffacher, Cynthia V et al. (2018) Conformational Dynamics in the Binding-Protein-Independent Mutant of the Escherichia coli Maltose Transporter, MalG511, and Its Interaction with Maltose Binding Protein. Biochemistry 57:3003-3015
Alvarez, Frances Joan D; Orelle, Cédric; Huang, Yan et al. (2015) Full engagement of liganded maltose-binding protein stabilizes a semi-open ATP-binding cassette dimer in the maltose transporter. Mol Microbiol 98:878-94
Chen, Jue (2013) Molecular mechanism of the Escherichia coli maltose transporter. Curr Opin Struct Biol 23:492-8
Oldham, Michael L; Chen, Shanshuang; Chen, Jue (2013) Structural basis for substrate specificity in the Escherichia coli maltose transport system. Proc Natl Acad Sci U S A 110:18132-7
Chen, Shanshuang; Oldham, Michael L; Davidson, Amy L et al. (2013) Carbon catabolite repression of the maltose transporter revealed by X-ray crystallography. Nature 499:364-8
Rice, Austin J; Alvarez, Frances J D; Schultz, Kathryn M et al. (2013) EPR spectroscopy of MolB2C2-a reveals mechanism of transport for a bacterial type II molybdate importer. J Biol Chem 288:21228-35
Richet, Evelyne; Davidson, Amy L; Joly, Nicolas (2012) The ABC transporter MalFGK(2) sequesters the MalT transcription factor at the membrane in the absence of cognate substrate. Mol Microbiol 85:632-47
Cui, Jinming; Davidson, Amy L (2011) ABC solute importers in bacteria. Essays Biochem 50:85-99
Oldham, Michael L; Chen, Jue (2011) Crystal structure of the maltose transporter in a pretranslocation intermediate state. Science 332:1202-5
Oldham, Michael L; Chen, Jue (2011) Snapshots of the maltose transporter during ATP hydrolysis. Proc Natl Acad Sci U S A 108:15152-6

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