Deconstruction of the Ras switching cycle through saturation mutagenesis

作者：Bandaru Pradeep; Shah Neel H; Bhattacharyya Moitrayee; Barton John P; Kondo Yasushi; Cofsky Joshua C; Gee Christine L; Chakraborty Arup K; Kortemme Tanja; Ranganathan Rama^*; Kuriyan John^*

来源：eLife, 2017, 6: e27810.

DOI：10.7554/eLife.27810

Ras proteins are highly conserved signaling molecules that exhibit regulated, nucleotide-dependent switching between active and inactive states. The high conservation of Ras requires mechanistic explanation, especially given the general mutational tolerance of proteins. Here, we use deep mutational scanning, biochemical analysis and molecular simulations to understand constraints on Ras sequence. Ras exhibits global sensitivity to mutation when regulated by a GTPase activating protein and a nucleotide exchange factor. Removing the regulators shifts the distribution of mutational effects to be largely neutral, and reveals hotspots of activating mutations in residues that restrain Ras dynamics and promote the inactive state. Evolutionary analysis, combined with structural and mutational data, argue that Ras has co-evolved with its regulators in the vertebrate lineage. Overall, our results show that sequence conservation in Ras depends strongly on the biochemical network in which it operates, providing a framework for understanding the origin of global selection pressures on proteins.

• 出版日期2017-7-7
• 单位河北医科大学