Optimization of Conformational Dynamics in an Epistatic Evolutionary Trajectory

ABRIATA LA; GONZALEZ MM; VILA AJ; TOMATIS PE

MOLECULAR BIOLOGY AND EVOLUTION

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2016 vol. 33 p. 1768 - 1776

0737-4038

The understanding of protein evolution depends on the ability to relate the impact of mutations on molecular traits toorganismal fitness. Biological activity and robustness have been regarded as important features in shaping proteinevolutionary landscapes. Conformational dynamics, which is essential for protein function, has received little attentionin the context of evolutionary analyses. Here we employ NMR spectroscopy, the chief experimental tool to describeprotein dynamics at atomic level in solution at room temperature, to study the intrinsic dynamic features of ametallo-blactamaseenzyme and three variants identified during a directed evolution experiment that led to an expanded substrateprofile. We show that conformational dynamics in the catalytically relevant microsecond to millisecond timescale isoptimized along the favored evolutionary trajectory. In addition, we observe that the effects of mutations on dynamicsare epistatic. Mutation Gly262Ser introduces slow dynamics on several residues that surround the active site whenintroduced in the wild-type enzyme. Mutation Asn70Ser removes the slow dynamics observed for few residues of thewild-type enzyme, but increases the number of residues that undergo slow dynamics when introduced in the Gly262Sermutant. These effects on dynamics correlate with the epistatic interaction between these two mutations on the bacterialphenotype. These findings indicate that conformational dynamics is an evolvable trait, and that proteins endowed withmore dynamic active sites also display a larger potential for promoting evolution.