IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
artículos
Título:
Adaptive protein evolution grants organismal fitness by improving catalysis and flexibility
Autor/es:
PABLO E. TOMATIS; STELLA M. FABIANE; FABIO SIMONA; PAOLO CARLONI; BRIAN J. SUTTON; ALEJANDRO J. VILA
Revista:
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Editorial:
National Academy of Sciences
Referencias:
Año: 2008 vol. 105 p. 20605 - 20610
ISSN:
0027-8424
Resumen:
Protein evolution is crucial for organismal adaptation and fitness.This process takes place by shaping a given 3-dimensional fold forits particular biochemical function within the metabolic requirementsand constraints of the environment. The complex interplaybetween sequence, structure, functionality, and stability that givesrise to a particular phenotype has limited the identification of traitsacquired through evolution. This is further complicated by the factthat mutations are pleiotropic, and interactions between mutationsare not always understood. Antibiotic resistance mediatedby beta-lactamases represents an evolutionary paradigm in whichorganismal fitness depends on the catalytic efficiency of asingle enzyme. Based on this, we have dissected the structuraland mechanistic features acquired by an optimized metallo-beta-lactamase (MBL) obtained by directed evolution. We show thatantibiotic resistance mediated by this enzyme is driven by 2mutations with sign epistasis. One mutation stabilizes a catalyticallyrelevant intermediate by fine tuning the position of 1 metalion; whereas the other acts by augmenting the protein flexibility.We found that enzyme evolution (and the associated antibioticresistance) occurred at the expense of the protein stability, revealingthat M beta Ls have not exhausted their stability threshold. Ourresults demonstrate that flexibility is an essential trait that can beacquired during evolution on stable protein scaffolds. Directedevolution aided by a thorough characterization of the selectedproteins can be successfully used to predict future evolutionaryevents and design inhibitors with an evolutionary perspective.