Journal article

A GTPase Chimera Illustrates an Uncoupled Nucleotide Affinity and Release Rate, Providing Insight into the Activation Mechanism

Amy P Guilfoyle, Chandrika N Deshpande, Josep Font Sadurni, Miriam-Rose Ash, Samuel Tourle, Gerhard Schenk, Megan J Maher, Mika Jormakka



The release of GDP from GTPases signals the initiation of a GTPase cycle, where the association of GTP triggers conformational changes promoting binding of downstream effector molecules. Studies have implicated the nucleotide-binding G5 loop to be involved in the GDP release mechanism. For example, biophysical studies on both the eukaryotic Gα proteins and the GTPase domain (NFeoB) of prokaryotic FeoB proteins have revealed conformational changes in the G5 loop that accompany nucleotide binding and release. However, it is unclear whether this conformational change in the G5 loop is a prerequisite for GDP release, or, alternatively, the movement is a consequence of release. To gain additional..

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University of Melbourne Researchers


Awarded by National Health and Medical Research Council

Awarded by National Cancer Institute

Awarded by National Institute of General Medical Sciences

Awarded by National Breast Cancer Foundation

Funding Acknowledgements

The National Health and Medical Research Council (grants No. APP632703 and No. APP1035693) supported this study. This research was undertaken on the MX2 beamline at the Australian Synchrotron, Victoria, Australia (16) and the GM/CA-CAT beamline 23-ID at the Advanced Photon Source, which is supported by National Cancer Institute grant No. Y1-CO-1020 and National Institute of General Medical Sciences grant No. Y1-GM-1104. C.N.D. is supported by a National Breast Cancer Foundation Postdoctoral Fellowship. G.S. is supported by an Australian Research Council Future Fellowship.