Genomic changes and the importance of the chaperonin GroEL in the evolution of highly bottlenecked bacterial populations

Resumen del póster presentado al Society for Molecular Biology and Evolution Meeting (SMBEv), celebrado de forma virtual del 3 al 8 de julio de 2021.Chaperones are involved in the folding of nascent client proteins, the prevention of polypeptides aggregation, the rescue of unfolded clients due to environmental stresses and act as an evolutionary driver due to their mutational buffering capacities. Major insect lineages have independently acquired bacterial species, mainly from Gamma-proteobacteria and Bacteroidetes class. These bacterial species could act as nutritional mutualistic factories, facultative mutualists that protect against biotic and abiotic stresses, or reproductive manipulators. Common trade among them is an increased level of genetic drift due to the small population size and the continuous population bottlenecking at each generation, processes that have shaped their genome, proteome, and morphology. Depending on the nature of the relationship, the degree of genome plasticity varies, i.e., obligate nutritional mutualistic symbionts have extremely small genomes lacking mobile elements, bacteriophages, and/or recombination machinery. Under these conditions, endosymbionts face high mutational pressures that may lead to extinction or symbiont replacement. How do they then survive for such a long evolutionary time, and why do they show genome stasis? Here we will focus on the genome changes suffered by these endosymbionts, by comparing them to their free-living relatives, and on the mutational robustness mechanisms, including the moonlighting chaperone GroEL that could explain their long prevalence from an evolutionary perspective by using experimental evolution of E. coli to simulate the effect of high groEL overexpression and strong genetic drift.Peer reviewe