title: Genomic and proteomic characterization of two novel siphovirus infecting the sedentary facultative epibiont cyanobacterium Acaryochloris marina.
abstract: Acaryochloris marina is a symbiotic species of cyanobacteria that is capable of utilizing far-red light. We report the characterization of the phages A-HIS1 and A-HIS2, capable of infecting Acaryochloris. Morphological characterization of these phages places them in the family Siphoviridae. However, molecular characterization reveals that they do not show genetic similarity with any known siphoviruses. While the phages do show synteny between each other, the nucleotide identity between the phages is low at 45-67%, suggesting they diverged from each other some time ago. The greatest number of genes shared with another phage (a myovirus infecting marine Synechococcus) was four. Unlike most other cyanophages and in common with the Siphoviridae infecting Synechococcus, no photosynthesis-related genes were found in the genome. CRISPR (clustered regularly interspaced short palindromic repeats) spacers from the host Acaryochloris had partial matches to sequences found within the phages, which is the first time CRISPRs have been reported in a cyanobacterial/cyanophage system. The phages also encode a homologue of the proteobacterial RNase T. The potential function of RNase T in the mark-up or digestion of crRNA hints at a novel mechanism for evading the host CRISPR system.
authors.affiliation: Warwick Systems Biology Centre, Coventry, UK.
authors.forename: Yi-Wah
authors.initials: YW
authors.lastname: Chan
authors.affiliation: School of Life Sciences, University of Warwick, Coventry, UK.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Millard
authors.affiliation: Department of Physics, University of Warwick, Coventry, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Wheatley
authors.affiliation: Institute for Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.
authors.forename: Antony B
authors.initials: AB
authors.lastname: Holmes
authors.affiliation: Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany.
authors.forename: Remus
authors.initials: R
authors.lastname: Mohr
authors.affiliation: Department of Chemistry, University of Warwick, Coventry, UK.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Whitworth
authors.affiliation: School of Life Sciences, University of Warwick, Coventry, UK.
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Mann
authors.affiliation: School of Biological Sciences, University of Sydney, Sydney, NSW, Australia.
authors.forename: Anthony W D
authors.initials: AW
authors.lastname: Larkum
authors.affiliation: Institute of Biology III, University of Freiburg, Freiburg, Germany.
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Hess
authors.affiliation: School of Life Sciences, University of Warwick, Coventry, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Scanlan
authors.affiliation: Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, LE19HN, UK.
authors.forename: Martha R J
authors.initials: MR
authors.lastname: Clokie
mesh_terms: D064112:Clustered Regularly Interspaced Short Palindromic Repeats / Q000235:genetics; D005095:Exoribonucleases / Q000235:genetics*; D016679:Genome, Viral / Q000235:genetics*; D023281:Genomics; D008969:Molecular Sequence Data; D040901:Proteomics; D017906:Siphoviridae / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D046940:Synechococcus / Q000235:genetics / Q000821:virology*; D026801:Synteny
chemical_list: D005095:Exoribonucleases; C042081:exoribonuclease T