Disruption of the Unique ABCG-Family NBD:NBD Interface Impacts Both Drug Transport and ATP Hydrolysis

ABCG2 is one of a triumvirate of human multidrug ATP binding cassette (ABC) transporters that are implicated in the defense of cells and tissues against cytotoxic chemicals, but these transporters can also confer chemotherapy resistance states in oncology. Understanding the mechanism of ABCG2 is thu...

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Bibliographic Details
Published in:International journal of molecular sciences 2020-01, Vol.21 (3), p.759
Main Authors: Kapoor, Parth, Briggs, Deborah A, Cox, Megan H, Kerr, Ian D
Format: Article
Language:English
Subjects:
abc transporter
ABC transporters
Adenosine triphosphatase
Adenosine triphosphate
Allosteric properties
atpase
Binding
C-Terminus
Chemoresistance
Chemotherapy
Cytotoxicity
Domains
Flow cytometry
Hydrolysis
Interfaces
Investigations
Isoforms
Localization
molecular mechanism
multidrug resistance
Mutation
nucleotide binding domain
Nucleotides
pharmacology
Physiology
Proteins
Residues
structure
Transmembrane domains
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Summary:ABCG2 is one of a triumvirate of human multidrug ATP binding cassette (ABC) transporters that are implicated in the defense of cells and tissues against cytotoxic chemicals, but these transporters can also confer chemotherapy resistance states in oncology. Understanding the mechanism of ABCG2 is thus imperative if we are to be able to counter its deleterious activity. The structure of ABCG2 and its related family members (ABCG5/G8) demonstrated that there were two interfaces between the nucleotide binding domains (NBD). In addition to the canonical ATP "sandwich-dimer" interface, there was a second contact region between residues at the C-terminus of the NBD. We investigated this second interface by making mutations to a series of residues that are in close interaction with the opposite NBD. Mutated ABCG2 isoforms were expressed in human embryonic kidney (HEK) 293T cells and analysed for targeting to the membrane, drug transport, and ATPase activity. Mutations to this second interface had a number of effects on ABCG2, including altered drug specificity, altered drug transport, and, in two mutants, a loss of ATPase activity. The results demonstrate that this region is particularly sensitive to mutation and can impact not only direct, local NBD events (i.e., ATP hydrolysis) but also the allosteric communication to the transmembrane domains and drug transport.
ISSN:1422-0067
1661-6596
1422-0067
DOI:10.3390/ijms21030759