1svk
From Proteopedia
(New page: 200px<br /><applet load="1svk" size="450" color="white" frame="true" align="right" spinBox="true" caption="1svk, resolution 2.00Å" /> '''Structure of the K18...) |
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| - | [[Image:1svk.gif|left|200px]]<br /><applet load="1svk" size=" | + | [[Image:1svk.gif|left|200px]]<br /><applet load="1svk" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1svk, resolution 2.00Å" /> | caption="1svk, resolution 2.00Å" /> | ||
'''Structure of the K180P mutant of Gi alpha subunit bound to AlF4 and GDP'''<br /> | '''Structure of the K180P mutant of Gi alpha subunit bound to AlF4 and GDP'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Heterotrimeric G protein alpha (G alpha) subunits possess intrinsic GTPase | + | Heterotrimeric G protein alpha (G alpha) subunits possess intrinsic GTPase activity that leads to functional deactivation with a rate constant of approximately 2 min(-1) at 30 degrees C. GTP hydrolysis causes conformational changes in three regions of G alpha, including Switch I and Switch II. Mutation of G202-->A in Switch II of G alpha(i1) accelerates the rates of both GTP hydrolysis and conformational change, which is measured by the loss of fluorescence from Trp-211 in Switch II. Mutation of K180-->P in Switch I increases the rate of conformational change but decreases the GTPase rate, which causes transient but substantial accumulation of a low-fluorescence G alpha(i1).GTP species. Isothermal titration calorimetric analysis of the binding of (G202A)G alpha(i1) and (K180P)G alpha(i1) to the GTPase-activating protein RGS4 indicates that the G202A mutation stabilizes the pretransition state-like conformation of G alpha(i1) that is mimicked by the complex of G alpha(i1) with GDP and magnesium fluoroaluminate, whereas the K180P mutation destabilizes this state. The crystal structures of (K180P)G alpha(i1) bound to a slowly hydrolyzable GTP analog, and the GDP.magnesium fluoroaluminate complex provide evidence that the Mg(2+) binding site is destabilized and that Switch I is torsionally restrained by the K180P mutation. The data are consistent with a catalytic mechanism for G alpha in which major conformational transitions in Switch I and Switch II are obligate events that precede the bond-breaking step in GTP hydrolysis. In (K180P)G alpha(i1), the two events are decoupled kinetically, whereas in the native protein they are concerted. |
==About this Structure== | ==About this Structure== | ||
| - | 1SVK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rattus_norvegicus Rattus norvegicus] with MG, ALF and GDP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Heterotrimeric_G-protein_GTPase Heterotrimeric G-protein GTPase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.6.5.1 3.6.5.1] Full crystallographic information is available from [http:// | + | 1SVK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rattus_norvegicus Rattus norvegicus] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=ALF:'>ALF</scene> and <scene name='pdbligand=GDP:'>GDP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Heterotrimeric_G-protein_GTPase Heterotrimeric G-protein GTPase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.6.5.1 3.6.5.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SVK OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Du, X.]] | [[Category: Du, X.]] | ||
[[Category: Li, P.]] | [[Category: Li, P.]] | ||
| - | [[Category: Ross, E | + | [[Category: Ross, E M.]] |
| - | [[Category: Sprang, S | + | [[Category: Sprang, S R.]] |
| - | [[Category: Thomas, C | + | [[Category: Thomas, C J.]] |
[[Category: Wang, Y.]] | [[Category: Wang, Y.]] | ||
[[Category: ALF]] | [[Category: ALF]] | ||
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[[Category: k180p mutation]] | [[Category: k180p mutation]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:05:38 2008'' |
Revision as of 13:05, 21 February 2008
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Structure of the K180P mutant of Gi alpha subunit bound to AlF4 and GDP
Overview
Heterotrimeric G protein alpha (G alpha) subunits possess intrinsic GTPase activity that leads to functional deactivation with a rate constant of approximately 2 min(-1) at 30 degrees C. GTP hydrolysis causes conformational changes in three regions of G alpha, including Switch I and Switch II. Mutation of G202-->A in Switch II of G alpha(i1) accelerates the rates of both GTP hydrolysis and conformational change, which is measured by the loss of fluorescence from Trp-211 in Switch II. Mutation of K180-->P in Switch I increases the rate of conformational change but decreases the GTPase rate, which causes transient but substantial accumulation of a low-fluorescence G alpha(i1).GTP species. Isothermal titration calorimetric analysis of the binding of (G202A)G alpha(i1) and (K180P)G alpha(i1) to the GTPase-activating protein RGS4 indicates that the G202A mutation stabilizes the pretransition state-like conformation of G alpha(i1) that is mimicked by the complex of G alpha(i1) with GDP and magnesium fluoroaluminate, whereas the K180P mutation destabilizes this state. The crystal structures of (K180P)G alpha(i1) bound to a slowly hydrolyzable GTP analog, and the GDP.magnesium fluoroaluminate complex provide evidence that the Mg(2+) binding site is destabilized and that Switch I is torsionally restrained by the K180P mutation. The data are consistent with a catalytic mechanism for G alpha in which major conformational transitions in Switch I and Switch II are obligate events that precede the bond-breaking step in GTP hydrolysis. In (K180P)G alpha(i1), the two events are decoupled kinetically, whereas in the native protein they are concerted.
About this Structure
1SVK is a Single protein structure of sequence from Rattus norvegicus with , and as ligands. Active as Heterotrimeric G-protein GTPase, with EC number 3.6.5.1 Full crystallographic information is available from OCA.
Reference
Uncoupling conformational change from GTP hydrolysis in a heterotrimeric G protein alpha-subunit., Thomas CJ, Du X, Li P, Wang Y, Ross EM, Sprang SR, Proc Natl Acad Sci U S A. 2004 May 18;101(20):7560-5. Epub 2004 May 5. PMID:15128951
Page seeded by OCA on Thu Feb 21 15:05:38 2008
Categories: Heterotrimeric G-protein GTPase | Rattus norvegicus | Single protein | Du, X. | Li, P. | Ross, E M. | Sprang, S R. | Thomas, C J. | Wang, Y. | ALF | GDP | MG | Active form | Gi alpha subunit | K180p mutation
