1XEF

Crystal structure of the ATP/Mg2+ bound composite dimer of HlyB-NBD

Summary for 1XEF

• Entry DOI: 10.2210/pdb1xef/pdb
• Descriptor: Alpha-hemolysin translocation ATP-binding protein hlyB, MAGNESIUM ION, ADENOSINE-5'-TRIPHOSPHATE, ... (4 entities in total)
• Functional Keywords: abc-transporter, atpase, haemolysin b, atp-dependent transport protein, transport protein
• Biological source: Escherichia coli
• Cellular location: Cell inner membrane; Multi-pass membrane protein (Probable): P08716
• Total number of polymer chains: 4
• Total formula weight: 109553.54

Authors

Zaitseva, J.,Jenewein, S.,Holland, I.B.,Schmitt, L. (deposition date: 2004-09-10, release date: 2005-06-07, Last modification date: 2023-10-25)

Primary citation

Zaitseva, J.,Jenewein, S.,Jumpertz, T.,Holland, I.B.,Schmitt, L.
H662 is the linchpin of ATP hydrolysis in the nucleotide-binding domain of the ABC transporter HlyB
Embo J., 24:1901-1910, 2005

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.

PubMed: 15889153
DOI: 10.1038/sj.emboj.7600657

Experimental method

X-RAY DIFFRACTION (2.5 Å)