MEINI Maria Rocio
Quantitative Description of a Protein Fitness Landscape based on Molecular Features
MARÍA ROCÍO MEINI; PABLO E. TOMATIS; DANIEL WEINREICH; ALEJANDRO J. VILA
MOLECULAR BIOLOGY AND EVOLUTION
OXFORD UNIV PRESS
Lugar: Oxford; Año: 2015 vol. 32 p. 1774 - 1787
Understanding the driving forces behind protein evolution requires the ability to correlate the molecular impact of mutations with organismal fitness. To address this issue, we employ here metallo-beta-lactamases as model system, which are Zn(II) dependant enzymes that mediate antibiotic resistance. We present a study of all the possible evolutionary pathways leading to a metallo-beta-lactamase variant optimized by directed evolution. By studying the activity, stability and Zn(II) binding capabilities of all mutants in the preferred evolutionary pathways, we show that this local fitness landscape is strongly conditioned by epistatic interactions arising from the pleiotropic effect of mutations in the different molecular features of the enzyme. In vitro activity and stability assays do not provide explanatory power. Instead, measurement of these molecular features in an environment resembling the native one provides an accurate description of the observed antibiotic resistance profile. We report that optimization of Zn(II) binding abilities of metallo-beta-lactamases during evolution is more critical than stabilization of the protein to enhance fitness. A global analysis of these parameters allows us to connect genotype with fitness based on quantitative molecular features.