Linear Megaplasmids Spreading in the Andean Resistome

Abstract

High-altitude wetlands and lakes in the Argentinean Puna are extreme and pristine environments. Bacteria living in such habitats must adapt to extremely harsh conditions, such as oligotrophy, high ultraviolet radiation, and high arsenic concentrations, among others. Commonly, genetic traits that confer resistance to the above factors could be encoded in extrachromosomal elements. In actinobacteria isolated from these high-altitude habitats, screening for plasmids has revealed the presence of novel linear megaplasmids for the genera Micrococcus and Brevibacterium. These linear replicons belong to a class of elements called invertrons, which are characterized by terminal inverted repeats and terminal proteins covalently attached to the DNA 5′ ends. Nucleotide sequencing studies of these linear plasmids has shown the presence of genes required for the survival in these particular habitats.