A shifty stop for a hairy tail

Phage Annotation Guide: Guidelines for Assembly and High-Quality Annotation

All sequencing projects of bacteriophages (phages) should seek to report an accurate and comprehensive annotation of their genomes. This article defines 14 questions for those new to phage genomics that should be addressed before submitting a genome sequence to the International Nucleotide Sequence Database Collaboration or writing a publication.

Isolation and characterisation of novel phages infecting Lactobacillus plantarum and proposal of a new genus, "Silenusvirus"

Bacteria of Lactobacillus sp. are very useful to humans. However, the biology and genomic diversity of their (bacterio)phage enemies remains understudied. Knowledge on Lactobacillus phage diversity should broaden to develop efficient phage control strategies. To this end, organic waste samples were screened for phages against two wine-related Lactobacillus plantarum strains. Isolates were shotgun sequenced and compared against the phage database and each other by phylogenetics and comparative genomics. The new isolates had only three distant relatives from the database, but displayed a high overall degree of genomic similarity amongst them. The latter allowed for the use of one isolate as a representative to conduct transmission electron microscopy and structural protein sequencing, and to study phage adsorption and growth kinetics. The microscopy and proteomics tests confirmed the observed diversity of the new isolates and supported their classification to the family Siphoviridae and the proposal of the new phage genus "Silenusvirus".

The genomes and comparative genomics of Lactobacillus delbrueckii phages

Lactobacillus delbrueckii phages are a great source of genetic diversity. Here, the genome sequences of Lb. delbrueckii phages LL-Ku, c5 and JCL1032 were analyzed in detail, and the genetic diversity of Lb. delbrueckii phages belonging to different taxonomic groups was explored. The lytic isometric group b phages LL-Ku (31,080 bp) and c5 (31,841 bp) showed a minimum nucleotide sequence identity of 90% over about three-fourths of their genomes. The genomic locations of their lysis modules were unique, and the genomes featured several putative overlapping transcription units of genes. LL-Ku and c5 virions displayed peptidoglycan hydrolytic activity associated with a ~36-kDa protein similar in size to the endolysin. Unexpectedly, the 49,433-bp genome of the prolate phage JCL1032 (temperate, group c) revealed a conserved gene order within its structural genes. Lb. delbrueckii phages representing groups a (a phage LL-H), b and c possessed only limited protein sequence homology. Genomic comparison of LL-Ku and c5 suggested that diversification of Lb. delbrueckii phages is mainly due to insertions, deletions and recombination. For the first time, the complete genome sequences of group b and c Lb. delbrueckii phages are reported.

Brochothrix thermosphacta bacteriophages feature heterogeneous and highly mosaic genomes and utilize unique prophage insertion sites

Brochothrix belongs to the low-GC branch of Gram-positive bacteria (Firmicutes), closely related to Listeria, Staphylococcus, Clostridium, and Bacillus. Brochothrix thermosphacta is a nonproteolytic food spoilage organism, adapted to growth in vacuum-packaged meats. We report the first genome sequences and characterization of Brochothrix bacteriophages. Phage A9 is a myovirus with an 89-nm capsid diameter and a 171-nm contractile tail; it belongs to the Spounavirinae subfamily and shares significant homologies with Listeria phage A511, Staphylococcus phage Twort, and others. The A9 unit genome is 127 kb long with 11-kb terminal redundancy; it encodes 198 proteins and 6 tRNAs. Phages BL3 and NF5 are temperate siphoviruses with a head diameter of 56 to 59 nm. The BL3 tail is 270 nm long, whereas NF5 features a short tail of only 94 nm. The NF5 genome (36.95 kb) encodes 57 gene products, BL3 (41.52 kb) encodes 65 products, and both are arranged in life cycle-specific modules. Surprisingly, BL3 and NF5 show little relatedness to Listeria phages but rather demonstrate relatedness to lactococcal phages. Peptide mass fingerprinting of viral proteins indicate programmed -1 translational frameshifts in the NF5 capsid and the BL3 major tail protein. Both NF5 and BL3 feature circularly permuted, terminally redundant genomes, packaged by a headful mechanism, and integrases of the serine (BL3) and tyrosine (NF5) types. They utilize unique target sequences not previously described: BL3 inserts into the 3' end of a RNA methyltransferase, whereas NF5 integrates into the 5'-terminal part of a putative histidinol-phosphatase. Interestingly, both genes are reconstituted by phage sequence.