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1f3o
From Proteopedia
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'''Crystal structure of MJ0796 ATP-binding cassette''' | '''Crystal structure of MJ0796 ATP-binding cassette''' | ||
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[[Category: Hunt, J F.]] | [[Category: Hunt, J F.]] | ||
[[Category: Yuan, Y R.]] | [[Category: Yuan, Y R.]] | ||
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Revision as of 12:51, 2 May 2008
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. 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 Page seeded by OCA on Fri May 2 15:51:20 2008
