title: Unraveling the genome structure of cyanobacterial podovirus A-4L with long direct terminal repeats.
abstract: The freshwater cyanobacterial virus (cyanophage) A-4L, a podovirus, can infect the model cyanobacterium Anabaena sp. strain PCC 7120 resulting in a high burst size and forming concentric plaques on its lawns. The complete genome sequence of A-4L was determined by the combination of high-throughput sequencing, terminal transferase-mediated polymerase chain reaction and restriction mapping. It contains 41,750 bp with 810 bp direct terminal repeats and 38 potential open reading frames. As compared with other cyanobacterial podoviruses in diverse ecosystems, the A-4L has the longest terminal repeat and shares similar genome organizations with freshwater members. Furthermore, phylogenetic analysis based on concatenated sequences of eight core proteins indicated that freshwater cyanobacterial podoviruses were clustered together and distinct from marine counterparts, suggesting a clear divergence in the cyanobacterial podovirus lineage between freshwater and marine ecosystems. Our findings uncover the unique genome structure of A-4L which contains long direct terminal repeats, and create the first model system to address knowledge gaps in understanding cyanobacterial virus-host interactions at the molecular level.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Ou
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Xiang-Yong
authors.initials: XY
authors.lastname: Liao
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Xiao-Chan
authors.initials: XC
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Xu-Dong
authors.initials: XD
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Wuhan 430072, China. Electronic address: zhangqy@ihb.ac.cn.
authors.forename: Qi-Ya
authors.initials: QY
authors.lastname: Zhang
mesh_terms: D017033:Anabaena / Q000821:virology*; D016000:Cluster Analysis; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D023061:Gene Order; D016679:Genome, Viral; D059014:High-Throughput Nucleotide Sequencing; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D017902:Podoviridae / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D020079:Terminal Repeat Sequences
chemical_list: D004279:DNA, Viral
keywords: Cyanobacterial podovirus A-4L; Cyanobacterial virus–host model system; Cyanophage; Genomic analysis; Terminal repeat