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Crystal structure of MJ0796 ATP-binding cassette
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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