Jumbo Bacteriophages: An Overview

Abstract

Tailed bacteriophages with genomes larger than 200 kbp are classified as Jumbo phages, and are rarely isolated by conventional methods. These phages are designated “jumbo” owing to their most notable features of a large phage virion and large genome size. However, in addition to these, jumbo phages also exhibit several novel characteristics that have not been observed for phages with smaller genomes, which differentiate jumbo phages in terms of genome organization, virion structure, progeny propagation, and evolution. In this review, we summarize available reports on jumbo phages and discuss the differences between jumbo phages and small-genome phages. We also discuss data suggesting that jumbo phages might have evolved from phages with smaller genomes by acquiring additional functional genes, and that these additional genes reduce the dependence of the jumbo phages on the host bacteria.

Genome-resolved viral and cellular metagenomes revealed potential key virus-host interactions in a deep freshwater lake

“…5 and S8). However, it is possible that their planktonic virions could have been included in the cellular fraction, because large virions of jumbo phage may be captured by the 0.22 µm poresized filter (Yuan and Gao, 2017). By contrast, the two other predicted LD12 viruses (LBVG_76 and LBVG_174) were abundant in both the cellular and virion fractions ( Figs.…”

“…Atu_ph07 (Attai et al, 2018) in their jumbo phage marker genes (Yuan and Gao, 2017): terminase large subunit (amino acid sequence identity = 52.6%), major capsid protein (58.3%), and DNA polymerase family B (43.8%). These results suggest that LBVG_1 is a jumbo phage infecting the LD12 lineage.…”

Integrative omics analysis ofPseudomonas aeruginosavirus PA5oct highlights the molecular complexity of jumbo phages

“…In terms of annotation, functions could be attributed for a third of PA5oct proteins and a large portion of predicted CDS are unique, lacking sequence-based similarity to the genomes available in the public database Genbank (r231). For this reason, the functional characterization of jumbo phage orphan genes is an important endeavor to undertake in order to elucidate basic phage biology as well as phage application safety when thinking of therapeutic settings (Yuan et al, 2017). Leveraging RNA-seq for a whole genome analysis is a powerful way to elucidate differential expression of gene features across different conditions but also delineate possible phage transcriptional modules.…”

“…Importantly, the large capsids seen in jumbo phages can accommodate large genomes allowing these phages to possess many accessory genes comparing to small phages (Ceyssens et al, 2014;Yuan & Gao, 2017;Mesyanzhinov et al, 2002;Hertveldt et al, 2005;Kiljunen et al, 2005;Thomas et al, 2007;Gill et al, 2012). For example, PA5oct encodes five different genes encoding peptidoglycan-degrading enzymes and 12 tRNA genes to increase the translation efficiency (Yuan & Gao, 2016…”

“…Bacteriophages with genome sizes beyond 200 kbp are known as jumbo phages, sometimes also referred to as giant phages. They have been isolated from a multitude of environments, including water, soil, plants, and animal tissues (Yuan et al, 2017). A subset of 120 of them have been sequenced to date (May 2019, Supplementary Table S1), including 109 myoviruses, 10 siphoviruses, and 1 unclassified phage.…”