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In vitro interaction between components of the inner membrane complex of the maltose ABC transporter of Escherichia coli : modulation by ATP
Author(s) -
Mourez Michaël,
Jéhanno Muguette,
Schneider Erwin,
Dassa Elie
Publication year - 1998
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1998.01070.x
Subject(s) - biology , atp binding cassette transporter , atp hydrolysis , transmembrane domain , biochemistry , maltose binding protein , inner membrane , transmembrane protein , conformational change , membrane protein , plasma protein binding , bacterial outer membrane , transporter , escherichia coli , microbiology and biotechnology , atpase , receptor , membrane , enzyme , recombinant dna , fusion protein , gene
Interactions between domains of ATP‐binding cassette (ABC) transporters are of great functional importance and yet are poorly understood. To gain further knowledge of these protein–protein interactions, we studied the inner membrane complex of the maltose transporter of Escherichia coli . We focused on interactions between the nucleotide‐binding protein, MalK, and the transmembrane proteins, MalF and MalG. We incubated purified MalK with inverted membrane vesicles containing MalF and MalG. MalK bound specifically to MalF and MalG and reconstituted a functional complex. We used this approach and limited proteolysis with trypsin to show that binding and hydrolysis of ATP, inducing conformational changes in MalK, modulate its interaction with MalF and MalG. MalK in the reconstituted complex was less sensitive to protease added from the cytoplasmic side of the membrane, and one proteolytic cleavage site located in the middle of a putative helical domain of MalK was protected. These results suggest that the putative helical domain of the nucleotide‐binding domains is involved, through its conformational changes, in the coupling between the transmembrane domains and ATP binding/hydrolysis at the nucleotide‐binding domains.