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| {{STRUCTURE_1f3o| PDB=1f3o | SCENE= }} | | {{STRUCTURE_1f3o| PDB=1f3o | SCENE= }} |
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| '''Crystal structure of MJ0796 ATP-binding cassette'''
| | ===Crystal structure of MJ0796 ATP-binding cassette=== |
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| ==Overview==
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| 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. | | The line below this paragraph, {{ABSTRACT_PUBMED_11402022}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11402022 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11402022}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Yuan, Y R.]] | | [[Category: Yuan, Y R.]] |
| [[Category: Transporter]] | | [[Category: Transporter]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 15:51:20 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 02:37:31 2008'' |
