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Crystal structure of the ATP/Mg2+ bound composite dimer of HlyB-NBDCrystal structure of the ATP/Mg2+ bound composite dimer of HlyB-NBD
Structural highlights
FunctionHLYBP_ECOLX Part of the ABC transporter complex HlyBD involved in hemolysin export. Transmembrane domains (TMD) form a pore in the inner membrane and the ATP-binding domain (NBD) is responsible for energy generation. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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. H662 is the linchpin of ATP hydrolysis in the nucleotide-binding domain of the ABC transporter HlyB.,Zaitseva J, Jenewein S, Jumpertz T, Holland IB, Schmitt L EMBO J. 2005 Jun 1;24(11):1901-10. Epub 2005 May 12. PMID:15889153[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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