title: Characterization of a novel domain 'GATE' in the ABC protein DrrA and its role in drug efflux by the DrrAB complex.
abstract: A novel domain, GATE (Glycine-loop And Transducer Element), is identified in the ABC protein DrrA. This domain shows sequence and structural conservation among close homologs of DrrA as well as distantly-related ABC proteins. Among the highly conserved residues in this domain are three glycines, G215, G221 and G231, of which G215 was found to be critical for stable expression of the DrrAB complex. Other conserved residues, including E201, G221, K227 and G231, were found to be critical for the catalytic and transport functions of the DrrAB transporter. Structural analysis of both the previously published crystal structure of the DrrA homolog MalK and the modeled structure of DrrA showed that G215 makes close contacts with residues in and around the Walker A motif, suggesting that these interactions may be critical for maintaining the integrity of the ATP binding pocket as well as the complex. It is also shown that G215A or K227R mutation diminishes some of the atomic interactions essential for ATP catalysis and overall transport function. Therefore, based on both the biochemical and structural analyses, it is proposed that the GATE domain, located outside of the previously identified ATP binding and hydrolysis motifs, is an additional element involved in ATP catalysis.
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Sadia
authors.initials: S
authors.lastname: Rahman
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Guoxing
authors.initials: G
authors.lastname: Fu
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA, 30303, USA. Electronic address: pkaur@gsu.edu.
authors.forename: Parjit
authors.initials: P
authors.lastname: Kaur
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004317:Doxorubicin / Q000493:pharmacokinetics; D024901:Drug Resistance, Multiple, Bacterial; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D005998:Glycine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D055550:Protein Stability; D017434:Protein Structure, Tertiary
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C101895:DrrA protein, Bacteria; C529122:DrrB protein, Escherichia coli; D029968:Escherichia coli Proteins; C489398:MalK protein, E coli; D004317:Doxorubicin; D000255:Adenosine Triphosphate; D005998:Glycine
keywords: ABC transporter; C-terminal domain; Doxorubicin efflux; DrrAB; Drug resistance; Nucleotide binding domain