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bioRxiv · 10.1101/2024.11.14.623250

RhoA Allosterically Activates Phospholipase Cε via its EF Hands

Ohri, V.·Samassekou, K.·Muralidharan, K.·Garland-Kuntz, E. E.·Fisher, I. J.·Hogan, W. C.·Davis, B. M.·Lyon, A.
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Abstract

Phospholipase C{varepsilon} (PLC{varepsilon}) cleaves phosphatidylinositol lipids to increase intracellular Ca2+ and activate protein kinase C (PKC) in response to stimulation of cell surface receptors. PLC{varepsilon} is activated via direct binding of small GTPases at the cytoplasmic leaflets of cellular membranes. In the cardiovascular system, the RhoA GTPase regulates PLC{varepsilon} to initiate a pathway that protects against ischemia/reperfusion injuries, but the underlying molecular mechanism is not known. We present here the cryo-electron microscopy (cryo-EM) reconstruction of RhoA bound to PLC{varepsilon}, showing that the G protein binds a unique insertion within the PLC{varepsilon} EF hands. Deletion of or mutations to this PLC{varepsilon} insertion decrease RhoA-dependent activation without impacting regulation by other G proteins. Together, our data support a model wherein RhoA binding to PLC{varepsilon} allosterically activates the lipase and increases its interactions with the membrane, resulting in maximum activity and cardiomyocyte survival.

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Ohri, V., Samassekou, K., Muralidharan, K., Garland-Kuntz, E. E., Fisher, I. J., Hogan, W. C., Davis, B. M., Lyon, A.. 2024-11-14. RhoA Allosterically Activates Phospholipase Cε via its EF Hands. https://doi.org/10.1101/2024.11.14.623250

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