1oix: Difference between revisions
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==Overview== | ==Overview== | ||
GTP hydrolysis by small GTP binding proteins of the Ras superfamily is a, universal reaction that controls multiple cellular regulations. Its, enzymic mechanism has been the subject of long-standing debates as to the, existence/identity of the general base and the electronic nature of its, transition state. Here we report the high-resolution crystal structure of, a small GTP binding protein, Rab11, solved in complex with GDP and Pi., Unexpectedly, a Pi oxygen and the GDP-cleaved oxygen are located less than, 2.5 A apart, suggesting that they share a proton, likely in the form of a, low-barrier hydrogen bond. This implies that the gamma-phosphate of GTP, was protonated; hence, that GTP acts as a general base. Furthermore, this, interaction should establish at, and stabilize, the transition .. | GTP hydrolysis by small GTP binding proteins of the Ras superfamily is a, universal reaction that controls multiple cellular regulations. Its, enzymic mechanism has been the subject of long-standing debates as to the, existence/identity of the general base and the electronic nature of its, transition state. Here we report the high-resolution crystal structure of, a small GTP binding protein, Rab11, solved in complex with GDP and Pi., Unexpectedly, a Pi oxygen and the GDP-cleaved oxygen are located less than, 2.5 A apart, suggesting that they share a proton, likely in the form of a, low-barrier hydrogen bond. This implies that the gamma-phosphate of GTP, was protonated; hence, that GTP acts as a general base. Furthermore, this, interaction should establish at, and stabilize, the transition state., Altogether, we propose a revised model for the GTPase reaction that should, reconcile earlier models into a unique substrate-assisted mechanism. | ||
==About this Structure== | ==About this Structure== | ||
1OIX is a | 1OIX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with PO4, MG, CL and GDP as [http://en.wikipedia.org/wiki/ligands ligands]. Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1OIX OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: small g protein]] | [[Category: small g protein]] | ||
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 13:53:38 2007'' | ||
