1f3o
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(New page: 200px<br /><applet load="1f3o" size="450" color="white" frame="true" align="right" spinBox="true" caption="1f3o, resolution 2.70Å" /> '''Crystal structure of...)
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Revision as of 12:27, 20 November 2007
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Crystal structure of MJ0796 ATP-binding cassette
Overview
The crystal structure of the MJ0796 ATP-binding cassette, a member of the, o228/LolD transporter family, has been determined at 2.7-A resolution with, MgADP bound at its active site. Comparing this structure with that of the, ATP-bound form of the HisP ATP-binding cassette (Hung, L. W., Wang, I. X., Nikaido, K., Liu, P. Q., Ames, G. F., and Kim, S. H. (1998) Nature 396, 703-707) shows a 5-A withdrawal of a phylogenetically invariant glutamine, residue from contact with the gamma-phosphate of ATP in the active site., This glutamine is located in a protein segment that links the rigid, F(1)-type ATP-binding core of the enzyme to an ABC transporter-specific, alpha-helical subdomain that moves substantially away from the active site, in the MgADP-bound structure of MJ0796 compared with the ATP-bound, structure of HisP. A similar conformational effect is observed in the, MgADP-bound structure of MJ1267 (Karpowich, N., et al. (2001) Structure, in press), establishing the withdrawal of the glutamine and the coupled, outward rotation of the alpha-helical subdomain as consistent consequences, of gamma-phosphate release from the active site of the transporter., Considering this subdomain movement in the context of a leading model for, the physiological dimer of cassettes present in ABC transporters indicates, that it produces a modest mechanical change that is likely to play a role, in facilitating nucleotide exchange out of the ATPase active site., Finally, it is noteworthy that one of the intersubunit packing, interactions in the MJ0796 crystal involves antiparallel beta-type, hydrogen bonding interactions between the outermost beta-strands in the, two core beta-sheets, leading to their fusion into a single extended, beta-sheet, a type of structural interaction that has been proposed to, play a role in mediating the aggregation of beta-sheet-containing, proteins.
About this Structure
1F3O is a Single protein structure of sequence from Methanocaldococcus jannaschii with MG and ADP as ligands. Full crystallographic information is available from OCA.
Reference
The crystal structure of the MJ0796 ATP-binding cassette. Implications for the structural consequences of ATP hydrolysis in the active site of an ABC transporter., Yuan YR, Blecker S, Martsinkevich O, Millen L, Thomas PJ, Hunt JF, J Biol Chem. 2001 Aug 24;276(34):32313-21. Epub 2001 Jun 11. PMID:11402022
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