Organisms Commons^™

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 …

Reporting Charcoal Rot In Chia And Developing A Susceptibility Assay, Reis M. Misaka, Hagop S. Atamian Dr., Julien Besnard Dr.

Student Scholar Symposium Abstracts and Posters

Chia (Salvia Hispanica) cross breeds were planted in the summer of 2018 with the intent of selective breeding for agricultural benefit. Preexisting pathogens in the soil caused 40-50% fatality of adult plants. This was surprising due to the precursory knowledge that chia has antibiotic and antifungal oils (Elshafie et. al. 2018); chia was only recently documented to be susceptible to Fusarium wilt (Fusarium oxysporum). The primary pathogen responsible was identified as Macrophomina phaseolina (aka charcoal rot); a widespread soilborne pathogen which has multiple commercial hosts (Su et. al. 2001).

M. phaesolina on wheat seed vector where used as …

Chloroviruses Lure Hosts Through Long-Distance Chemical Signaling, David Dunigan, Maitham Ahmed Al-Sammak, Zeina Al-Ameeli, Irina Agarkova, John Delong, James L. Van Etten

James Van Etten Publications

Chloroviruses exist in aquatic systems around the planet where they infect certain eukaryotic green algae that are mutualistic endosymbionts in a variety of protists and metazoans. Natural chlorovirus populations are seasonally dynamic but the precise temporal changes in these populations and the mechanisms that underlie them have, heretofore, been unclear. We recently reported the novel concept that predator/prey-mediated virus activation regulates chlorovirus population dynamics, and in the current manuscript demonstrate virus packaged chemotactic modulation of prey behavior.

Viruses have not previously been reported to act as chemotactic/chemo-attractive agents. Rather, viruses as extracellular entities are generally viewed as non-metabolically active spore-like …

The N-Glycan Structures Of The Antigenic Variants Of Chlorovirus Pbcv-1 Major Capsid Protein Help To Identify The Virus-Encoded Glycosyltransferases, Immacolata Speciale, Garry A. Duncan, Luca Unione, Irina Agarkova, Domenico Garozzo, Jesus Jimenez-Barbero, Sicheng Lin, Todd L. Lowary, Antonio Molinaro, Eric Noel, Maria Elena Laugieri, Michela Tonetti, James L. Van Etten, Cristina De Castro

James Van Etten Publications

The chlorovirus Paramecium bursaria chlorella virus 1 (PBCV-1) is a large dsDNA virus that infects the microalga Chlorella variabilis NC64A. Unlike most other viruses, PBCV-1 encodes most, if not all, of the machinery required to glycosylate its major capsid protein (MCP). The structures of the four N-linked glycans from the PBCV-1 MCP consist of nonasaccharides, and similar glycans are not found elsewhere in the three domains of life. Here, we identified the roles of three virus-encoded glycosyltransferases (GTs) that have four distinct GT activities in glycan synthesis. Two of the three GTs were previously annotated as GTs but the third …

Repeat Elements Organise 3d Genome Structure And Mediate Transcription In The Filamentous Fungus Epichloë Festucae, David J. Winter, Austen R. D. Ganley, Carolyn A. Young, Ivan Liachko, Christopher L. Schardl, Pierre-Yves Dupont, Daniel Berry, Arvina Ram, Barry Scott, Murray P. Cox

Plant Pathology Faculty Publications

Structural features of genomes, including the three-dimensional arrangement of DNA in the nucleus, are increasingly seen as key contributors to the regulation of gene expression. However, studies on how genome structure and nuclear organisation influence transcription have so far been limited to a handful of model species. This narrow focus limits our ability to draw general conclusions about the ways in which three-dimensional structures are encoded, and to integrate information from three-dimensional data to address a broader gamut of biological questions. Here, we generate a complete and gapless genome sequence for the filamentous fungus, Epichloë festucae. We use Hi-C …

Capsid Structure Of Dsrna Fungal Viruses, Daniel Luque, Carlos P. Mata, Nobuhiro Suzuki, Said A. Ghabrial, José R. Castón

Plant Pathology Faculty Publications

Most fungal, double-stranded (ds) RNA viruses lack an extracellular life cycle stage and are transmitted by cytoplasmic interchange. dsRNA mycovirus capsids are based on a 120-subunit T = 1 capsid, with a dimer as the asymmetric unit. These capsids, which remain structurally undisturbed throughout the viral cycle, nevertheless, are dynamic particles involved in the organization of the viral genome and the viral polymerase necessary for RNA synthesis. The atomic structure of the T = 1 capsids of four mycoviruses was resolved: the L-A virus of Saccharomyces cerevisiae (ScV-L-A), Penicillium chrysogenum virus (PcV), Penicillium stoloniferum virus F (PsV-F), and Rosellinia necatrix …

Genes For Membrane Transport Proteins: Not So Rare In Viruses, Timo Greiner, Anna Moroni, James L. Van Etten, Gerhard Thiel

James Van Etten Publications

Some viruses have genes encoding proteins with membrane transport functions. It is unknown if these types of proteins are rare or are common in viruses. In particular, the evolutionary origin of some of the viral genes is obscure, where other viral proteins have homologs in prokaryotic and eukaryotic organisms. We searched virus genomes in databases looking for transmembrane proteins with possible transport function. This effort led to the detection of 18 different types of putative membrane transport proteins indicating that they are not a rarity in viral genomes. The most abundant proteins are K+ channels. Their predicted structures vary between …

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 …

Biophysical Approaches To Solve The Structures Of The Complex Glycan Shield Of Chloroviruses, Cristina De Castro, Garry Duncan, Domenico Garozzo, Antonio Molinaro, Luisa Sturiale, Michela Tonetti, James L. Van Etten

James Van Etten Publications

The capsid of Paramecium bursaria chlorella virus (PBCV-1) contains a heavily glycosylated major capsid protein, Vp54. The capsid protein contains four glycans, each N-linked to Asn. The glycan structures are unusual in many aspects: (1) they are attached by a β-glucose linkage, which is rare in nature; (2) they are highly branched and consist of 8–10 neutral monosaccharides; (3) all four glycoforms contain a dimethylated rhamnose as the capping residue of the main chain, a hyper-branched fucose residue and two rhamnose residues ''with opposite absolute configurations; (4) the four glycoforms differ by the nonstoichiometric presence of two monosaccharides, l-arabinose and …

Acquisition Of Functions On The Outer Capsid Surface During Evolution Of Double-Stranded Rna Fungal Viruses, Carlos P. Mata, Daniel Luque, Josué Gómez-Blanco, Javier M. Rodríguez, José M. González, Nobuhiro Suzuki, Said A. Ghabrial, José L. Carrascosa, Benes L. Trus, José R. Castón

Plant Pathology Faculty Publications

Unlike their counterparts in bacterial and higher eukaryotic hosts, most fungal viruses are transmitted intracellularly and lack an extracellular phase. Here we determined the cryo-EM structure at 3.7 Å resolution of Rosellinia necatrix quadrivirus 1 (RnQV1), a fungal double-stranded (ds)RNA virus. RnQV1, the type species of the family Quadriviridae, has a multipartite genome consisting of four monocistronic segments. Whereas most dsRNA virus capsids are based on dimers of a single protein, the ~450-Å-diameter, T = 1 RnQV1 capsid is built of P2 and P4 protein heterodimers, each with more than 1000 residues. Despite a lack of sequence similarity between …

Multiple Origins Of Endosymbionts In Chlorellaceae With No Reductive Effects On The Plastid Or Mitochondrial Genomes, Weishu Fan, Wenhu Guo, James L. Van Etten, Jeffrey P. Mower

James Van Etten Publications

Ancient endosymbiotic relationships have led to extreme genomic reduction in many bacterial and eukaryotic algal endosymbionts. Endosymbionts in more recent and/or facultative relationships can also experience genomic reduction to a lesser extent, but little is known about the effects of the endosymbiotic transition on the organellar genomes of eukaryotes. To understand how the endosymbiotic lifestyle has affected the organellar genomes of photosynthetic green algae, we generated the complete plastid genome (plastome) and mitochondrial genome (mitogenome) sequences from three green algal endosymbionts (Chlorella heliozoae, Chlorella variabilis and Micractinium conductrix). The mitogenomes and plastomes of the three newly sequenced endosymbionts …

The Role Of Co-Opted Escrt Proteins And Lipid Factors In Protection Of Tombusviral Double-Stranded Rna Replication Intermediate Against Reconstituted Rnai In Yeast, Nikolay Kovalev, Jun-Ichi Inaba, Zhenghe Li, Peter D. Nagy

Plant Pathology Faculty Publications

Reconstituted antiviral defense pathway in surrogate host yeast is used as an intracellular probe to further our understanding of virus-host interactions and the role of co-opted host factors in formation of membrane-bound viral replicase complexes in protection of the viral RNA against ribonucleases. The inhibitory effect of the RNA interference (RNAi) machinery of S. castellii, which only consists of the two-component DCR1 and AGO1 genes, was measured against tomato bushy stunt virus (TBSV) in wild type and mutant yeasts. We show that deletion of the co-opted ESCRT-I (endosomal sorting complexes required for transport I) or ESCRT-III factors makes …

Induction And Suppression Of Antiviral Rna Silencing By Tomato Spotted Wilt Virus, Sergio M. Gabriel Peralta

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Tomato spotted wilt virus (TSWV) is an emerging pathogen with wide host range and one of the most important viruses of plants. Information regarding processing of negative single stranded RNA viruses such as TSWV in the RNA silencing pathway remains limited. In nature TSWV is only transmitted by thrips as vectors and since infection occurs in both thrips and plants, an experimental system to transmit using thrips and the detection of TSWV were established. In order to understand the processing of TSWV in the RNA silencing pathway, Arabidopsis thaliana as a model plant was used in the genetic analysis against …

Swainsonine Biosynthesis Genes In Diverse Symbiotic And Pathogenic Fungi, Daniel Cook, Bruno G. G. Donzelli, Rebecca Creamer, Deana L. Baucom, Dale R. Gardner, Juan Pan, Neil Moore, Stuart B. Krasnoff, Jerzy W. Jaromczyk, Christopher L. Schardl

Plant Pathology Faculty Publications

Swainsonine—a cytotoxic fungal alkaloid and a potential cancer therapy drug—is produced by the insect pathogen and plant symbiont Metarhizium robertsii, the clover pathogen Slafractonia leguminicola, locoweed symbionts belonging to Alternaria sect. Undifilum, and a recently discovered morning glory symbiont belonging to order Chaetothyriales. Genome sequence analyses revealed that these fungi share orthologous gene clusters, designated “SWN,” which included a multifunctional swnKgene comprising predicted adenylylation and acyltransferase domains with their associated thiolation domains, a β-ketoacyl synthase domain, and two reductase domains. The role of swnK was demonstrated by inactivating it in M. robertsii through homologous …

Identification Of Intrahelical Bifurcated H‑Bonds As A New Type Of Gate In K+ Channels, Oliver Rauh, Martin Urban, Leonhard M. Henkes, Tobias Winterstein, Timo Greiner, James L. Van Etten, Anna Moroni, Stefan M. Kast, Gerhard Thiel, Indra Schroeder

James Van Etten Publications

Gating of ion channels is based on structural transitions between open and closed states. To uncover the chemical basis of individual gates, we performed a comparative experimental and computational analysis between two K⁺ channels, Kcv_S and Kcv_NTS. These small viral encoded K+ channel proteins, with a monomer size of only 82 amino acids, resemble the pore module of all complex K+ channels in terms of structure and function. Even though both proteins share about 90% amino acid sequence identity, they exhibit different open probabilities with ca. 90% in Kcv_NTS and 40% in Kcv_S. …

Virus-Mediated Suppression Of Host Non-Self Recognition Facilitates Horizontal Transmission Of Heterologous Viruses, Songsong Wu, Jiasen Cheng, Yanping Fu, Tao Chen, Daohong Jiang, Said A. Ghabrial, Jiatao Xie

Plant Pathology Faculty Publications

Non-self recognition is a common phenomenon among organisms; it often leads to innate immunity to prevent the invasion of parasites and maintain the genetic polymorphism of organisms. Fungal vegetative incompatibility is a type of non-self recognition which often induces programmed cell death (PCD) and restricts the spread of molecular parasites. It is not clearly known whether virus infection could attenuate non-self recognition among host individuals to facilitate its spread. Here, we report that a hypovirulence-associated mycoreovirus, named Sclerotinia sclerotiorum mycoreovirus 4 (SsMYRV4), could suppress host non-self recognition and facilitate horizontal transmission of heterologous viruses. We found that cell death in …

Draft Genome Sequence Of Cercospora Sojina Isolate S9, A Fungus Causing Frogeye Leaf Spot (Fls) Disease Of Soybean, Fanchang Zeng, Chaofan Wang, Guirong Zhang, Junmei Wei, Carl A. Bradley, Ray Ming

Plant Pathology Faculty Publications

Fungi are the causal agents of many of the world's most serious plant diseases causing disastrous consequences for large-scale agricultural production. Pathogenicity genomic basis is complex in fungi as multicellular eukaryotic pathogens. The fungus Cercospora sojina is a plant pathogen that threatens global soybean supplies. Here, we report the genome sequence of C. sojina strain S9 and detect genome features and predicted genomic elements. The genome sequence of C. sojina is a valuable resource with potential in studying the fungal pathogenicity and soybean host resistance to frogeye leaf spot (FLS), which is caused by C. sojina. …

A Comparative Genomic Analysis Of Putative Pathogenicity Genes In The Host-Specific Sibling Species Colletotrichum Graminicola And Colletotrichum Sublineola, Ester A. S. Buiate, Katia Viana Xavier, Neil Moore, Maria F. Torres, Mark L. Farman, Christopher L. Schardl, Lisa J. Vaillancourt

Plant Pathology Faculty Publications

Background: Colletotrichum graminicola and C. sublineola cause anthracnose leaf and stalk diseases of maize and sorghum, respectively. In spite of their close evolutionary relationship, the two species are completely host-specific. Host specificity is often attributed to pathogen virulence factors, including specialized secondary metabolites (SSM), and small-secreted protein (SSP) effectors. Genes relevant to these categories were manually annotated in two co-occurring, contemporaneous strains of C. graminicola and C. sublineola. A comparative genomic and phylogenetic analysis was performed to address the evolutionary relationships among these and other divergent gene families in the two strains.

Results: Inoculation of maize with C. sublineola …

The Family Rhabdoviridae: Mono- And Bipartite Negative-Sense Rna Viruses With Diverse Genome Organization And Common Evolutionary Origins, Ralf G. Dietzgen, Hideki Kondo, Michael M. Goodin, Gael Kurath, Nikos Vasilakis

Plant Pathology Faculty Publications

The family Rhabdoviridae consists of mostly enveloped, bullet-shaped or bacilliform viruses with a negative-sense, single-stranded RNA genome that infect vertebrates, invertebrates or plants. This ecological diversity is reflected by the diversity and complexity of their genomes. Five canonical structural protein genes are conserved in all rhabdoviruses, but may be overprinted, overlapped or interspersed with several novel and diverse accessory genes. This review gives an overview of the characteristics and diversity of rhabdoviruses, their taxonomic classification, replication mechanism, properties of classical rhabdoviruses such as rabies virus and rhabdoviruses with complex genomes, rhabdoviruses infecting aquatic species, and plant rhabdoviruses with both mono- …

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 …

Structural Studies Demonstrating A Bacteriophage-Like Replication Cycle Of The Eukaryote-Infecting Paramecium Bursaria Chlorella Virus-1, Elad Milrot, Eyal Shimoni, Katya Rechav, Tamar Unger, James L. Van Etten, Abraham Minsky

James Van Etten Publications

A fundamental stage in viral infection is the internalization of viral genomes in host cells. Although extensively studied, the mechanisms and factors responsible for the genome internalization process remain poorly understood. Here we report our observations, derived from diverse imaging methods on genome internalization of the large dsDNA Paramecium bursaria chlorella virus-1 (PBCV-1). Our studies reveal that early infection stages of this eukaryotic- infecting virus occurs by a bacteriophage-like pathway, whereby PBCV-1 generates a hole in the host cell wall and ejects its dsDNA genome in a linear, base-pair-by-base-pair process, through a membrane tunnel generated by the fusion of the …

Conversion Of An Instantaneous Activating K+ Channel Into A Slow Activating Inward Rectifier, Dirk Baumeister, Brigitte Hertel, Indra Schroeder, Sabrina Gazzarrini, Stefan M. Kast, James L. Van Etten, Anna Moroni, Gerhard Thiel

James Van Etten Publications

The miniature channel, Kcv, is a structural equivalent of the pore of all K⁺ channels. Here, we follow up on a previous observation that a largely voltage-insensitive channel can be converted into a slow activating inward rectifier after extending the outer transmembrane domain by one Ala. This gain of rectification can be rationalized by dynamic salt bridges at the cytosolic entrance to the channel; opening is favored by voltage-sensitive formation of salt bridges and counteracted by their disruption. Such latent voltage sensitivity in the pore could be relevant for the understanding of voltage gating in complex Kv channels.

Structure Of The N-Glycans From The Chlorovirus Ne-Jv-1, Immacolata Speciale, Irina Agarkova, Garry Duncan, James L. Van Etten, Cristina De Castro

James Van Etten Publications

Results from recent studies are breaking the paradigm that all viruses depend on their host machinery to glycosylate their proteins. Chloroviruses encode several genes involved in glycan biosynthesis and some of their capsid proteins are decorated with N-linked oligosaccharides with unique features. Here we describe the elucidation of the N-glycan structure of an unusual chlorovirus, NE-JV-1, that belongs to the Pbi group. The host for NE-JV-1 is the zoochlorella Micractinium conductrix. Spectroscopic analyses established that this N-glycan consists of a core region that is conserved in all of the chloroviruses. The one difference is that the residue 3OMe-l-rhamnose is …

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 …

Climate Change And The Integrity Of Science, Peter H. Gleick, James L. Van Etten, Members Of The U.S. National Academy Of Sciences

James Van Etten Publications

We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular. All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything. When someone says that society should wait until scientists are absolutely certain before taking any action, it is the same as saying society should never take action. For a problem as potentially catastrophic as climate change, taking no action poses a dangerous risk for our planet.

Scientific conclusions derive from an understanding of basic laws supported by …

Three-Year Survey Of Abundance, Prevalence And Genetic Diversity Of Chlorovirus Populations In A Small Urban Lake, Cristian F. Quispe, Olivia Sonderman, Anya Seng, Brenna Rasmussen, Garrett Weber, Claire Mueller, David Dunigan, James L. Van Etten

James Van Etten Publications

Inland water environments cover about 2.5 percent of our planet and harbor huge numbers of known and still unknown microorganisms. In this report, we examined water samples for the abundance, prevalence, and genetic diversity of a group of infectious viruses (chloroviruses) that infect symbiotic chlorella-like green algae. Samples were collected on a weekly basis for a period of 24 to 36 months from a recreational freshwater lake in Lincoln, Nebraska, and assayed for infectious viruses by plaque assay. The numbers of infectious virus particles were both host- and site-dependent. The consistent fluctuations in numbers of viruses suggest their impact as …

Cell-Free And Cell-Based Approaches To Explore The Roles Of Host Membranes And Lipids In The Formation Of Viral Replication Compartment Induced By Tombusviruses, Peter D. Nagy, Judit Pogany, Kai Xu

Plant Pathology Faculty Publications

Plant positive strand RNA viruses are intracellular infectious agents that take advantage of cellular lipids and membranes to support replication and protect viral RNA from degradation by host antiviral responses. In this review, we discuss how Tomato bushy stunt virus (TBSV) co-opts lipid transfer proteins and modulates lipid metabolism and transport to facilitate the assembly of the membrane-bound viral replicase complexes within intricate replication compartments. Identification and characterization of the proviral roles of specific lipids and proteins involved in lipid metabolism based on results from yeast (Saccharomyces cerevisiae) model host and cell-free approaches are discussed. The review also …

Chloroviruses N-Linked Glycans Share A New Type Of Conserved Core Architecture Unprecedented In Any Form Of Life / [Published As] N-Linked Glycans Of Chloroviruses Sharing A Core Architecture Without Precedent, Cristina De Castro, Immacolata Speciale, Garry Duncan, David Dunigan, Irina Agarkova, Rosa Lanzetta, Luisa Sturiale, Angelo Palmigiano, Domenico Garozzo, Antonio Molinaro, Michela Tonetti, James L. Van Etten

James Van Etten Publications

N-glycosylation is a fundamental modification of proteins that exists in the three domains of life and in some viruses, including the chloroviruses, for which a new type of core N-glycan is described. This N-glycan core structure common to all chloroviruses is a pentasaccharide with a β-glucose linked to an asparagine residue that is not located in the typical sequon N-X-T/S. The glucose is linked to a terminal xylose unit and a hyperbranched fucose, in turn substituted with a terminal galactose and a second xylose residue. The third position of the fucose unit is always linked to a rhamnose, which is …

Virus–Host Interactions: Insights From The Replication Cycle Of The Large Paramecium Bursaria Chlorella Virus, Elad Milrot, Yael Mutsafi, Yael Fridmann-Sirkis, Eyal Shimoni, Katya Rechav, James Gurnon, James L. Van Etten, Abraham Minsky

James Van Etten Publications

The increasing interest in cytoplasmic factories generated by eukaryotic-infecting viruses stems from the realization that these highly ordered assemblies may contribute fundamental novel insights to the functional significance of order in cellular biology. Here, we report the formation process and structural features of the cytoplasmic factories of the large dsDNA virus Paramecium bursaria chlorella virus 1 (PBCV-1). By combining diverse imaging techniques, including scanning transmission electron microscopy tomography and focused ion beam technologies, we show that the architecture and mode of formation of PBCV-1 factories are significantly different from those generated by their evolutionary relatives Vaccinia and Mimivirus. Specifically, PBCV-1 …

Engineering Of A Light-Gated Potassium Channel, Christian Cosentino, Laura Alberio, Sabrina Gazzarrini, Marco Aquila, Eduardo Romano, Solei Cermenati, Paolo Zuccolini, Jan Petersen, Monica Beltrame, James L. Van Etten, John M. Christie, Gerhard Thiel, Anna Moroni

James Van Etten Publications

The present palette of opsin-based optogenetic tools lacks a light-gated potassium (K+) channel desirable for silencing of excitable cells. Here, we describe the construction of a blue-light–induced K+ channel 1 (BLINK1) engineered by fusing the plant LOV2-Ja photosensory module to the small viral K+ channel Kcv. BLINK1 exhibits biophysical features of Kcv, including K+ selectivity and high single-channel conductance, but reversibly photoactivates in blue light. Opening of BLINK1 channels hyperpolarizes the cell to the K+ equilibrium potential. Ectopic expression of BLINK1 reversibly inhibits the escape response in light-exposed zebrafish larvae. BLINK1 therefore provides a single-component optogenetic tool that can establish …