PMID:15889153
| Citation |
Zaitseva, J, Jenewein, S, Jumpertz, T, Holland, IB and Schmitt, L (2005) H662 is the linchpin of ATP hydrolysis in the nucleotide-binding domain of the ABC transporter HlyB. EMBO J. 24:1901-10 |
|---|---|
| Abstract |
The ABC transporter HlyB is a central element of the HlyA secretion machinery, a paradigm of Type I secretion. Here, we describe the crystal structure of the HlyB-NBD (nucleotide-binding domain) with H662 replaced by Ala in complex with ATP/Mg2+. The dimer shows a composite architecture, in which two intact ATP molecules are bound at the interface of the Walker A motif and the C-loop, provided by the two monomers. ATPase measurements confirm that H662 is essential for activity. Based on these data, we propose a model in which E631 and H662, highly conserved among ABC transporters, form a catalytic dyad. Here, H662 acts as a 'linchpin', holding together all required parts of a complicated network of interactions between ATP, water molecules, Mg2+, and amino acids both in cis and trans, necessary for intermonomer communication. Based on biochemical experiments, we discuss the hypothesis that substrate-assisted catalysis, rather than general base catalysis might operate in ABC-ATPases. |
| Links |
PubMed PMC1142601 Online version:10.1038/sj.emboj.7600657 |
| Keywords |
ATP-Binding Cassette Transporters/chemistry; ATP-Binding Cassette Transporters/metabolism; Adenosine Triphosphate/metabolism; Alanine/chemistry; Amino Acid Substitution; Binding Sites; Catalysis; Crystallography, X-Ray; Dimerization; Escherichia coli/enzymology; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/metabolism; Glutamic Acid/chemistry; Glutamine/chemistry; Hemolysin Proteins/chemistry; Hemolysin Proteins/metabolism; Histidine/chemistry; Histidine/physiology; Hydrogen Bonding; Hydrolysis; Models, Molecular; Protein Binding; Protein Conformation; Protein Structure, Tertiary; Structure-Activity Relationship |
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