Muramidase, nuclease, or hypothetical protein genes intervene between paired genes encoding DNA packaging terminase and portal proteins in Wolbachia phages and prophages

AbstractGenomes of the obligate intracellular alpha proteobacteriumWolbachia pipientis often encode prophage-like regions, and in a few cases, purified particles have been recovered. Because the structure of a conserved WO phage genome has been difficult to establish, we examined paired terminase and portal genes inWolbachia phages and prophages, relative to those encoded by the gene transfer agent RcGTA from the free-living alpha proteobacteriumRhodobacter capsulatus. Terminase and portal proteins fromWolbachia have higher similarity to orthologs encoded by RcGTA than to orthologs encoded by bacteriophage lambda. In lambdoid phages, these proteins play key roles in assembly of mature phage particles, while in less well-studied gene transfer agents, terminase and portal proteins package random fragments of bacterial DNA, which could confound elucidation of WO phage genomes. In WO phages and prophages, terminase genes followed by a short gpW gene may be separated from the downstream portal gene by open-reading frames encoding a GH_25 hydrolase/muramidase, a PD-(D/E)XK nuclease, a hypothetical protein and/or a RelE/ParE toxin-antitoxin module. These aspects of gene organization, coupled with evidence for a low, non-inducible yield of WO phages, and the small size of WO phage particles described in the literature raise the possibility thatWolbachia prophage regions participate in processes that extend beyond conventional bacteriophage lysogeny and lytic replication. These interv...

Source: Virus Genes - May 10, 2022 Category: Genetics & Stem Cells Source Type: research