Two inducible prophages of an antarctic Pseudomonas sp. ANT-H14 use the same capsid for packaging their genomes - Characterization of a novel phage helper-satellite system

Abstract

Two novel prophages φAH14a and φAH14b of a psychrotolerant Antarctic bacterium Pseudomonas sp. ANT-H14 have been characterized. They were simultaneously induced with mitomycin C and packed into capsids of the same size and protein composition. The genome sequences of φAH14a and φAH14b have been determined. φAH14b, the phage with a smaller genome (16,812 bp) seems to parasitize φAH14a (55,060 bp) and utilizes its capsids, as only the latter encodes a complete set of structural proteins. Both viruses probably constitute a phage helper-satellite system, analogous to the P2-P4 duo. This study describes the architecture and function of the φAH14a and φAH14b genomes. Moreover, a functional analysis of a φAH14a-encoded lytic enzyme and a DNA methyltransferase was performed. In silico analysis revealed the presence of the homologs of φAH14a and φAH14b in other Pseudomonas genomes, which may suggest that helper-satellite systems related to the one described in this work are common in pseudomonads.