A novel MMR pathway in prokaryotes

Comunicación presentada en la 26th Conference on Intelligent Systems for Molecular Biology, celebrada en Chicago (Estados Unidos) del 6 al 10 de julio de 2018.Mismatch repair pathway (MMR) is essential to maintain genome stability. While MutS and MutL are essential for performing the initial and steps of the route, those are missing in many Archaea, most Actinobacteria, and other prokaryotes. However, these organisms exhibit similar spontaneous mutation rates to those bearing the MMR proteins. We have reported NucS, as an endonuclease involved in Mismatch repair (MMR) with no structural homology to known MMR factors. By genetic screenings we found [1] that this protein is required for mutation avoidance and anti-recombination, hallmarks of the canonical MMR in the surrogate model Mycobacterium smegmatis, lacking classical MutS-MutL factors. Structural bioinformatics coupled to evolutionary studies of NucS indicate a complex making-up of the pathway that involved at least two horizontal gene transfers leading to a disperse distribution pattern in prokaryotes. Together, these findings indicate that distinct pathways for MMR have evolved at least twice in nature