1mt0
ATP-binding domain of haemolysin B from Escherichia coli
OverviewOverview
The ABC-transporter haemolysin B is a central component of the secretion machinery that translocates the toxin, haemolysin A, in a Sec-independent fashion across both membranes of E. coli. Here, we report the X-ray crystal structure of the nucleotide-binding domain (NBD) of HlyB. The molecule shares the common overall architecture of ABC-transporter NBDs. However, the last three residues of the Walker A motif adopt a 3(10) helical conformation, stabilized by a bound anion. In consequence, this results in an unusual interaction between the Walker A lysine residue and the Walker B glutamate residue. As these residues are normally required to be available for ATP binding, for catalysis and for dimer formation of ABC domains, we suggest that this conformation may represent a latent monomeric form of the NBD. Surprisingly, comparison of available NBD structures revealed a structurally diverse region (SDR) of about 30 residues within the helical arm II domain, unique to each of the eight NBDs analyzed. As this region interacts with the transmembrane part of ABC-transporters, the SDR helps to explain the selectivity and/or targeting of different NBDs to their cognate transmembrane domains.
About this StructureAbout this Structure
1MT0 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of the nucleotide-binding domain of the ABC-transporter haemolysin B: identification of a variable region within ABC helical domains., Schmitt L, Benabdelhak H, Blight MA, Holland IB, Stubbs MT, J Mol Biol. 2003 Jul 4;330(2):333-42. PMID:12823972 Page seeded by OCA on Sat May 3 01:41:03 2008