Restoration of the GTPase activity and cellular interactions of Gα <sub>o</sub> mutants by Zn <sup>2+</sup> in <i>GNAO1</i> encephalopathy models
Yonika Arum Larasati, Mikhail Savitsky, Alexey Koval, Gonzalo P. Solis, Jana Valnohová, Vladimir L. Katanaev
Abstract
De novo point mutations in GNAO1 , gene encoding the major neuronal G protein Gα o , have recently emerged in patients with pediatric encephalopathy having motor, developmental, and epileptic dysfunctions. Half of clinical cases affect codons Gly 203 , Arg 209 , or Glu 246 ; we show that these mutations accelerate GTP uptake and inactivate GTP hydrolysis through displacement Gln 205 critical for GTP hydrolysis, resulting in constitutive GTP binding by Gα o . However, the mutants fail to adopt the activated conformation and display aberrant interactions with signaling partners. Through high-throughput screening of approved drugs, we identify zinc pyrithione and Zn 2+ as agents restoring active conformation, GTPase activity, and cellular interactions of the encephalopathy mutants, with negligible effects on wild-type Gα o . We describe a Drosophila model of GNAO1 encephalopathy where dietary zinc restores the motor function and longevity of the mutant flies. Zinc supplements are approved for diverse human neurological conditions. Our work provides insights into the molecular etiology of GNAO1 encephalopathy and defines a potential therapy for the patients.