RhoA allosterically activates phospholipase Cε via its EF hands

Area of Science:

• Biochemistry
• Molecular Biology
• Cardiovascular Research

Background:

• Phospholipase Cε (PLCε) is activated by small GTPases, playing a role in cellular signaling.
• RhoA GTPase is known to regulate PLCε in the cardiovascular system, offering protection against ischemia/reperfusion injuries.
• The precise molecular mechanism of RhoA regulation of PLCε remains unknown.

Purpose of the Study:

• To elucidate the molecular mechanism by which RhoA GTPase activates PLCε.
• To characterize the structural basis of RhoA-PLCε interaction.
• To understand how this interaction contributes to cardioprotection.

Main Methods:

• Cryo-electron microscopy (cryo-EM) to determine the structure of RhoA bound to PLCε.
• Site-directed mutagenesis to investigate the role of a specific PLCε insertion.
• Biochemical assays to assess PLCε activation and membrane binding.

Main Results:

• The cryo-EM structure revealed that RhoA binds to a unique insertion within the EF hands of PLCε.
• Deletion or mutation of this insertion abolished RhoA-dependent PLCε activation.
• This interaction allosterically activates PLCε, increasing its membrane association and lipase activity.

Conclusions:

• RhoA binding to a specific PLCε insertion is critical for its activation.
• This interaction enhances PLCε membrane binding and activity, contributing to cardiomyocyte survival.
• The findings provide a molecular basis for RhoA-mediated cardioprotection via PLCε.