Isolation and characterization of AS-1, a phycovirus infecting the blue-green algae, Anacystis nidulans and Synechococcus cedrorum

Safferman, Robert S.; Diener, T.O.; Desjardins, Paul; Morris, Mary-Ellen

doi:10.1016/0042-6822(72)90243-7

Cited by 81 publications

(41 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The latent periods of other cyanophages published to date are 9 h for S-PM2 infecting Synechococcus sp. strain WH7803 (72), 7 h for the Nostoc virus N-1 (48), 8.5 h for the AS-1 virus of Synechococcus elongates (52), and 5 and 4 h for the two freshwater cyanophages Pf-WMP3 and Pf-WMP4, respectively (39,40). The burst size of Syn5 (20 to 30 PFU/cell) was comparable to those reported for marine cyanophage S-PM2.…”

Section: Discussionsupporting

confidence: 60%

See 1 more Smart Citation

Intracellular Assembly of Cyanophage Syn5 Proceeds through a Scaffold-Containing Procapsid

Raytcheva

Haase-Pettingell

Piret

et al. 2011

J Virol

View full text Add to dashboard Cite

Syn5 is a marine cyanophage that is propagated on the marine photosynthetic cyanobacterial strain Synechococcus sp. WH8109 under laboratory conditions. Cryoelectron images of this double-stranded DNA (dsDNA) phage reveal an icosahedral capsid with short tail appendages and a single novel hornlike structure at the vertex opposite the tail. Despite the major impact of cyanophages on life in the oceans, there is limited information on cyanophage intracellular assembly processes within their photosynthetic hosts. The one-step growth curve of Syn5 demonstrated a short cycle with an eclipse period of ϳ45 min, a latent phase of ϳ60 min, and a burst size of 20 to 30 particles per cell at 28°C. SDS-PAGE and Western blot analysis of cell lysates at different times after infection showed the synthesis of major virion proteins and their increase as the infection progressed. The scaffolding protein of Syn5, absent from virions, was identified in the lysates and expressed from the cloned gene. It migrated anomalously on SDS-PAGE, similar to the phage T7 scaffolding protein.Particles lacking DNA but containing the coat and scaffolding proteins were purified from Syn5-infected cells using CsCl centrifugation followed by sucrose gradient centrifugation. Electron microscopic images of the purified particles showed shells lacking condensed DNA but filled with protein density, presumably scaffolding protein. These findings suggest that the cyanophages form infectious virions through the initial assembly of scaffolding-containing procapsids, similar to the assembly pathways for the enteric dsDNA bacteriophages. Since cyanobacteria predate the enteric bacteria, this procapsid-mediated assembly pathway may have originated with the cyanophages.

show abstract

Section: Discussionsupporting

confidence: 60%

“…The phage growth cycle was considerably shorter than the doubling time of the host, which was about 15 h under the same conditions. The growth cycle of Syn5 is the most rapid among cyanophages reported to date (39,40,48,52,72). The average burst size in the triplicate data shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Intracellular Assembly of Cyanophage Syn5 Proceeds through a Scaffold-Containing Procapsid

Raytcheva

Haase-Pettingell

Piret

et al. 2011

J Virol

View full text Add to dashboard Cite

show abstract

“…Anacystis nidulans was grown and infected by cyanophage AS-l [6] as in [7]. Under the conditions used, the lytic cycle lasted for 6-8 h [8,9].…”

Section: Methodsmentioning

confidence: 99%

Redox modulation of glucose‐6‐P dehydrogenase in Anacystis nidulans and its ‘uncoupling’ by phage infection

1981

View full text Add to dashboard Cite

“…In addition, phylogenetic analysis has revealed that viruses in aquatic ecosystems are genetically diverse, suggesting that they are under significant selection pressure, perhaps in response to host defense systems and/or variations in the environment (22). Understanding how environmental factors and/or host genetics affect the success of viral infection is therefore relevant to the understanding of aquatic ecosystems.A previously characterized contractile DNA phage of Synechococcus elongatus named AS-1 is a member of the family Myoviridae, which includes the well-characterized T-even phages (11,(14)(15)(16) (Fig. 1A).…”

mentioning

confidence: 99%

Diel Infection of a Cyanobacterium by a Contractile Bacteriophage

Kao¹,

Green²,

Stein

et al. 2005

Appl Environ Microbiol

View full text Add to dashboard Cite

Light was found to strongly influence the infection of a freshwater cyanobacterium (Synechococcus elongatus PCC 7942) by a contractile DNA phage named AS-1. Phage progeny production was correlated with the amount of light in the laboratory and occurred in a diel pattern under natural light. At least one effect of light on AS-1 infection is at the level of adsorption.Viruses are present in marine and freshwater systems at more than 10 7 particles per milliliter (4,18). This large number argues strongly for an important role in global biological and geochemical processes, including the recycling of nutrient stores due to virus-induced lysis (4,6,13,20). In addition, phylogenetic analysis has revealed that viruses in aquatic ecosystems are genetically diverse, suggesting that they are under significant selection pressure, perhaps in response to host defense systems and/or variations in the environment (22). Understanding how environmental factors and/or host genetics affect the success of viral infection is therefore relevant to the understanding of aquatic ecosystems.A previously characterized contractile DNA phage of Synechococcus elongatus named AS-1 is a member of the family Myoviridae, which includes the well-characterized T-even phages (11,(14)(15)(16) (Fig. 1A). AS-1 infects the well-characterized freshwater obligate phototroph Synechococcus elongatus PCC 7942 (14). A key feature of S. elongatus biology is that its gene expression is regulated by an intrinsic ϳ24-h circadian clock (5,7,8). The products of three key genes, kaiA, kaiB, and kaiC, are required for maintaining the normal gene expression rhythm (7,8). Deletion of any of these three genes will result in a loss of rhythmicity but will not significantly affect growth rates (5). We were initially interested in examining whether mutations in circadian rhythm regulators of S. elongatus would affect AS-1 infection. We found that deletions in the genes that regulate S. elongatus circadian rhythm had only minor effects on AS-1 progeny production, whereas light had a profound influence on the AS-1 infection process. MATERIALS AND METHODSS. elongatus strain AMC541 is the parental strain for the circadian mutants. Strains AMC702, AMC703, and AMC704 have deletions in the kaiA, kaiB, and kaiC genes, respectively. Additional genetic information concerning the strains used can be found in the report of Ditty et al. (5). Cultures were usually grown under constant illumination at 45 mol photons m Ϫ2 s Ϫ1 in a modified BG-11 medium (2). Light intensity was measured with a LiCor luminometer. The original preparation of AS-1 was obtained from the American Type Culture Collection. A stock of at least 10 9 phage per ml was prepared by infecting S. elongatus grown in the presence of light for more than 18 h, followed by two clarifications of the supernatant of the culture lysate by centrifugation. The clarified lysate was stored at 4°C with a drop of chloroform. As previously determined by Safferman et al. (14), the lysate was stable for a minimum of several weeks at 4°C...

show abstract

Isolation and characterization of AS-1, a phycovirus infecting the blue-green algae, Anacystis nidulans and Synechococcus cedrorum

Cited by 81 publications

References 17 publications

Intracellular Assembly of Cyanophage Syn5 Proceeds through a Scaffold-Containing Procapsid

Intracellular Assembly of Cyanophage Syn5 Proceeds through a Scaffold-Containing Procapsid

Redox modulation of glucose‐6‐P dehydrogenase in Anacystis nidulans and its ‘uncoupling’ by phage infection

Diel Infection of a Cyanobacterium by a Contractile Bacteriophage

Contact Info

Product

Resources

About