1nbm: Difference between revisions
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==Overview== | ==Overview== | ||
BACKGROUND: F1-ATPase is the globular domain of F1F0-ATP synthase that | BACKGROUND: F1-ATPase is the globular domain of F1F0-ATP synthase that catalyses the hydrolysis of ATP to ADP and phosphate. The crystal structure of bovine F1-ATPase has been determined previously to 2.8 A resolution. The enzyme comprises five different subunits in the stoichiometry alpha 3 beta 3 gamma delta epsilon; the three catalytic beta subunits alternate with the three alpha subunits around the centrally located single gamma subunit. To understand more about the catalytic mechanisms, F1-ATPase was inhibited by reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) and the structure of the inhibited complex (F1-NBD) determined by X-ray crystallography. RESULTS: In the structure the three beta subunits adopt a different conformation with different nucleotide occupancy. NBD-Cl reacts with the phenolic oxygen of Tyr311 of the beta E subunit, which contains no bound nucleotide. The two other catalytic subunits beta TP and beta DP contain bound adenylyl-imidodiphosphate (AMP-PNP) and ADP, respectively. The binding site of the NBD moiety does not overlap with the regions of beta E that form the nucleotide-binding pocket in subunits beta TP and beta DP nor does it occlude the nucleotide-binding site. Catalysis appears to be inhibited because neither beta TP nor beta DP can accommodate a Tyr311 residue bearing an NBD group. CONCLUSIONS: The results presented here are consistent with a rotary catalytic mechanism of ATP synthesis and hydrolysis, which requires the sequential and concerted participation of all three catalytic sites. NBD-Cl inhibits the enzyme by preventing the modified subunit from adopting a conformation that is essential for catalysis to proceed. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Bos taurus]] | [[Category: Bos taurus]] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Transferred entry: 3 | [[Category: Transferred entry: 3 6.3 14]] | ||
[[Category: Braig, K.]] | [[Category: Braig, K.]] | ||
[[Category: Leslie, A | [[Category: Leslie, A G.W.]] | ||
[[Category: Orriss, G | [[Category: Orriss, G L.]] | ||
[[Category: Walker, J | [[Category: Walker, J E.]] | ||
[[Category: ADP]] | [[Category: ADP]] | ||
[[Category: ATP]] | [[Category: ATP]] | ||
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[[Category: inhibition]] | [[Category: inhibition]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:04:22 2008'' | ||
Revision as of 15:04, 21 February 2008
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THE STRUCTURE OF BOVINE F1-ATPASE COVALENTLY INHIBITED WITH 4-CHLORO-7-NITROBENZOFURAZAN
OverviewOverview
BACKGROUND: F1-ATPase is the globular domain of F1F0-ATP synthase that catalyses the hydrolysis of ATP to ADP and phosphate. The crystal structure of bovine F1-ATPase has been determined previously to 2.8 A resolution. The enzyme comprises five different subunits in the stoichiometry alpha 3 beta 3 gamma delta epsilon; the three catalytic beta subunits alternate with the three alpha subunits around the centrally located single gamma subunit. To understand more about the catalytic mechanisms, F1-ATPase was inhibited by reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) and the structure of the inhibited complex (F1-NBD) determined by X-ray crystallography. RESULTS: In the structure the three beta subunits adopt a different conformation with different nucleotide occupancy. NBD-Cl reacts with the phenolic oxygen of Tyr311 of the beta E subunit, which contains no bound nucleotide. The two other catalytic subunits beta TP and beta DP contain bound adenylyl-imidodiphosphate (AMP-PNP) and ADP, respectively. The binding site of the NBD moiety does not overlap with the regions of beta E that form the nucleotide-binding pocket in subunits beta TP and beta DP nor does it occlude the nucleotide-binding site. Catalysis appears to be inhibited because neither beta TP nor beta DP can accommodate a Tyr311 residue bearing an NBD group. CONCLUSIONS: The results presented here are consistent with a rotary catalytic mechanism of ATP synthesis and hydrolysis, which requires the sequential and concerted participation of all three catalytic sites. NBD-Cl inhibits the enzyme by preventing the modified subunit from adopting a conformation that is essential for catalysis to proceed.
About this StructureAbout this Structure
1NBM is a Protein complex structure of sequences from Bos taurus with , , and as ligands. Active as Transferred entry: 3.6.3.14, with EC number 3.6.1.34 Known structural/functional Sites: , , , , , , , , and . Full crystallographic information is available from OCA.
ReferenceReference
Bovine F1-ATPase covalently inhibited with 4-chloro-7-nitrobenzofurazan: the structure provides further support for a rotary catalytic mechanism., Orriss GL, Leslie AG, Braig K, Walker JE, Structure. 1998 Jul 15;6(7):831-7. PMID:9687365
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