Rapid de novo evolution of lysis genes in single-stranded RNA phages

Abstract

AbstractLeviviruses are bacteriophages with small single-stranded RNA genomes consisting of 3-4 genes, one of which (sgl) encodes a protein that induces the host to undergo autolysis and liberate progeny virions. Recent meta-transcriptomic studies have uncovered thousands of leviviral genomes, but most of these lack an annotatedsgl, mainly due to the small size, lack of sequence similarity, and embedded nature of these genes. Here, we identifysglgenes in 244 leviviral genomes and functionally characterize them inEscherichia coli. We show that leviviruses readily evolvesglgenes and sometimes have more than one per genome. Moreover, these genes share little to no similarity with each other or to previously knownsglgenes, thus representing a rich source for potential protein antibiotics.