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Mutations that alter the transmembrane signalling pathway in an ATP binding cassette (ABC) transporter.
Author(s) -
Covitz K.M.,
Panagiotidis C.H.,
Hor L.I.,
Reyes M.,
Treptow N.A.,
Shuman H.A.
Publication year - 1994
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1994.tb06439.x
Subject(s) - periplasmic space , biology , atp binding cassette transporter , biochemistry , membrane transport protein , atp hydrolysis , integral membrane protein , transport protein , walker motifs , membrane protein , protein subunit , microbiology and biotechnology , transmembrane protein , plasma protein binding , atpase , transporter , receptor , membrane , gene , escherichia coli , enzyme
The maltose transport system of Escherichia coli is a well‐characterized member of the ATP binding cassette transporter superfamily. Members of this family share sequence similarity surrounding two short sequences (the Walker A and B sequences) which constitute a nucleotide binding pocket. It is likely that the energy from binding and hydrolysis of ATP is used to accomplish the translocation of substrate from one location to another. Periplasmic binding protein‐dependent transport systems, like the maltose transport system of E.coli, possess a water‐soluble ligand binding protein that is essential for transport activity. In addition to delivering ligand to the membrane‐bound components of the system on the external face of the membrane, the interaction of the binding protein with the membrane complex initiates a signal that is transmitted to the ATP binding subunit on the cytosolic side and stimulates its hydrolytic activity. Mutations that alter the membrane complex so that it transports independently of the periplasmic binding protein also result in constitutive activation of the ATPase. Genetic analysis indicates that, in general, two mutations are required for binding protein‐independent transport and constitutive ATPase. The mutations alter residues that cluster to specific regions within the membrane spanning segments of the integral membrane components MalF and MalG. Individually, the mutations perturb the ability of MBP to interact productively with the membrane complex. Genetic alteration of this signalling pathway suggests that other agents might have similar effects. These could be potentially useful for modulating the activities of ABC transporters such as P‐glycoprotein or CFTR, that are implicated in disease.