title: Capturing the mutational landscape of the beta-lactamase TEM-1.
abstract: Adaptation proceeds through the selection of mutations. The distribution of mutant fitness effect and the forces shaping this distribution are therefore keys to predict the evolutionary fate of organisms and their constituents such as enzymes. Here, by producing and sequencing a comprehensive collection of 10,000 mutants, we explore the mutational landscape of one enzyme involved in the spread of antibiotic resistance, the beta-lactamase TEM-1. We measured mutation impact on the enzyme activity through the estimation of amoxicillin minimum inhibitory concentration on a subset of 990 mutants carrying a unique missense mutation, representing 64% of possible amino acid changes in that protein reachable by point mutation. We established that mutation type, solvent accessibility of residues, and the predicted effect of mutations on protein stability primarily determined alone or in combination changes in minimum inhibitory concentration of mutants. Moreover, we were able to capture the drastic modification of the mutational landscape induced by a single stabilizing point mutation (M182T) by a simple model of protein stability. This work thereby provides an integrated framework to study mutation effects and a tool to understand/define better the epistatic interactions.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM), Unité Mixte de Recherche en Santé (UMR-S) 722, F-75018 Paris, France. herve.jacquier@lrb.aphp.fr
authors.forename: Hervé
authors.initials: H
authors.lastname: Jacquier
authors.forename: André
authors.initials: A
authors.lastname: Birgy
authors.forename: Hervé
authors.initials: H
authors.lastname: Le Nagard
authors.forename: Yves
authors.initials: Y
authors.lastname: Mechulam
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Schmitt
authors.forename: Jérémy
authors.initials: J
authors.lastname: Glodt
authors.forename: Beatrice
authors.initials: B
authors.lastname: Bercot
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Petit
authors.forename: Julie
authors.initials: J
authors.lastname: Poulain
authors.forename: Guilène
authors.initials: G
authors.lastname: Barnaud
authors.forename: Pierre-Alexis
authors.initials: PA
authors.lastname: Gros
authors.forename: Olivier
authors.initials: O
authors.lastname: Tenaillon
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000465:Algorithms; D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004795:Enzyme Stability / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D019143:Evolution, Molecular; D008826:Microbial Sensitivity Tests; D008957:Models, Genetic; D009154:Mutation; D013696:Temperature; D013816:Thermodynamics; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D000658:Amoxicillin; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1
keywords: adaptive landscape; distribution of fitness effects; epistasis