RAS G-domains fine-tune the sorting of phosphatidylserine acyl chains in the plasma membrane

Abstract

AbstractMutant RAS are major contributors to cancer and signal from nanoclusters on the plasma membrane (PM), via isoform-specific membrane anchors. However, the same RAS isoform bound to different guanine nucleotides are segregated on the PM. Paradoxically, various segregated RAS nanoclusters all enrich a type of anionic phospholipid, phosphatidylserine (PS). These findings suggest intricate participation of RAS G-domains in their PM distribution, which have not been explored. We now show that wild-types, oncogenic G12V mutants and membrane anchors of isoforms HRAS, KRAS4A and KRAS4B sort distinct PS species. Mechanistically, shifting orientation states of KRAS4B G-domain exposes residues, such as Arg 73, Arg 102 and Arg 135, to the PM, and contributes to PS acyl chain sorting. Oncogenic mutations may shift orientation states of G-domains. We show that G12V, G12D, G12C, G13D and Q61H mutants of KRAS4B sort distinct PS species. Thus, RAS G-domains fine-tune their lateral distribution on the PM.