Download MendeleyH662 is the linchpin of ATP hydrolysis in the nucleotide-binding domain of the ABC transporter HlyB
Zaitseva, J., Jenewein, S., Jumpertz, T., Holland, I.B., Schmitt, L.(2005) EMBO J 24: 1901-1910
- PubMed: 15889153 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1038/sj.emboj.7600657
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1XEF - PubMed 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.
- Institute of Biochemistry, Biocenter, Johann-Wolfgang Goethe University Frankfurt, Frankfurt, Germany.
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