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Viruses

Chloroviruses

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Smrt Sequencing Of Paramecium Bursaria Chlorella Virus-1 Reveals Diverse Methylation Stability In Adenines Targeted By Restriction Modification Systems, Samantha R. Coy, Eric R. Gann, Spiridon E. Papoulis, Michael E. Holder, Nadim J. Ajami, Joseph F. Petrosino, Erik R. Zinser, James L. Van Etten, Steven W. Wilhelm May 2020

Smrt Sequencing Of Paramecium Bursaria Chlorella Virus-1 Reveals Diverse Methylation Stability In Adenines Targeted By Restriction Modification Systems, Samantha R. Coy, Eric R. Gann, Spiridon E. Papoulis, Michael E. Holder, Nadim J. Ajami, Joseph F. Petrosino, Erik R. Zinser, James L. Van Etten, Steven W. Wilhelm

James Van Etten Publications

Chloroviruses (family Phycodnaviridae) infect eukaryotic, freshwater, unicellular green algae. A unique feature of these viruses is an abundance of DNA methyltransferases, with isolates dedicating up to 4.5% of their protein coding potential to these genes. This diversity highlights just one of the long-standing values of the chlorovirus model system; where group-wide epigenomic characterization might begin to elucidate the function(s) of DNA methylation in large dsDNA viruses. We characterized DNA modifications in the prototype chlorovirus, PBCV-1, using single-molecule real time (SMRT) sequencing (aka PacBio). Results were compared to total available sites predicted in silico based on DNA sequence alone. SMRT-software detected …


Size-Dependent Catalysis Of Chlorovirus Population Growth By A Messy Feeding Predator, John Delong, Zeina Al-Ameeli, Shelby Lyon, James L. Van Etten, David Dunigan Jan 2018

Size-Dependent Catalysis Of Chlorovirus Population Growth By A Messy Feeding Predator, John Delong, Zeina Al-Ameeli, Shelby Lyon, James L. Van Etten, David Dunigan

James Van Etten Publications

Many chloroviruses replicate in endosymbiotic zoochlorellae that are protected from infection by their symbiotic host. To reach the high virus concentrations that often occur in natural systems, a mechanism is needed to release zoochlorellae from their hosts. We demonstrate that the ciliate predator Didinium nasutum foraging on zoochlorellae-bearing Paramecium bursaria can release live zoochlorellae from the ruptured prey cell that can then be infected by chloroviruses. The catalysis process is very effective, yielding roughly 95% of the theoretical infectious virus yield as determined by sonication of P. bursaria. Chlorovirus activation is more effective with smaller Didinia, as larger …


Structure Of The Chlorovirus Pbcv-1 Major Capsid Glycoprotein Determined By Combining Crystallographic And Carbohydrate Molecular Modeling Approaches, Cristina De Castro, Thomas Klose, Immacolata Speciale, Rosa Lanzetta, Antonio Molinaro, James L. Van Etten, Michael G. Rossmann Jan 2017

Structure Of The Chlorovirus Pbcv-1 Major Capsid Glycoprotein Determined By Combining Crystallographic And Carbohydrate Molecular Modeling Approaches, Cristina De Castro, Thomas Klose, Immacolata Speciale, Rosa Lanzetta, Antonio Molinaro, James L. Van Etten, Michael G. Rossmann

James Van Etten Publications

The glycans of the major capsid protein (Vp54) of Paramecium bursaria chlorella virus (PBCV-1) were recently described and found to be unusual. This prompted a reexamination of the previously reported Vp54 X-ray structure. A detailed description of the complete glycoprotein was achieved by combining crystallographic data with molecular modeling. The crystallographic data identified most of the monosaccharides located close to the protein backbone, but failed to detect those further from the glycosylation sites. Molecular modeling complemented this model by adding the missing monosaccharides and examined the conformational preference of the whole molecule, alone or within the crystallographic environment. Thus, combining …


Predators Catalyze An Increase In Chloroviruses By Foraging On The Symbiotic Hosts Of Zoochlorellae, John Delong, Zeina Al-Ameeli, Garry A. Duncan, James L. Van Etten, David D. Dunigan Ph. D. Nov 2016

Predators Catalyze An Increase In Chloroviruses By Foraging On The Symbiotic Hosts Of Zoochlorellae, John Delong, Zeina Al-Ameeli, Garry A. Duncan, James L. Van Etten, David D. Dunigan Ph. D.

James Van Etten Publications

Virus population growth depends on contacts between viruses and their hosts. It is often unclear how sufficient contacts are made between viruses and their specific hosts to generate spikes in viral abundance. Here, we show that copepods, acting as predators, can bring aquatic viruses and their algal hosts into contact. Specifically, predation of the protist Paramecium bursaria by copepods resulted in a >100-fold increase in the number of chloroviruses in 1 d. Copepod predation can be seen as an ecological “catalyst” by increasing contacts between chloroviruses and their hosts, zoochlorellae (endosymbiotic algae that live within paramecia), thereby facilitating viral population …