title: Ribonucleotide reductases reveal novel viral diversity and predict biological and ecological features of unknown marine viruses.
abstract: Virioplankton play a crucial role in aquatic ecosystems as top-down regulators of bacterial populations and agents of horizontal gene transfer and nutrient cycling. However, the biology and ecology of virioplankton populations in the environment remain poorly understood. Ribonucleotide reductases (RNRs) are ancient enzymes that reduce ribonucleotides to deoxyribonucleotides and thus prime DNA synthesis. Composed of three classes according to O2 reactivity, RNRs can be predictive of the physiological conditions surrounding DNA synthesis. RNRs are universal among cellular life, common within viral genomes and virioplankton shotgun metagenomes (viromes), and estimated to occur within >90% of the dsDNA virioplankton sampled in this study. RNRs occur across diverse viral groups, including all three morphological families of tailed phages, making these genes attractive for studies of viral diversity. Differing patterns in virioplankton diversity were clear from RNRs sampled across a broad oceanic transect. The most abundant RNRs belonged to novel lineages of podoviruses infecting α-proteobacteria, a bacterial class critical to oceanic carbon cycling. RNR class was predictive of phage morphology among cyanophages and RNR distribution frequencies among cyanophages were largely consistent with the predictions of the "kill the winner-cost of resistance" model. RNRs were also identified for the first time to our knowledge within ssDNA viromes. These data indicate that RNR polymorphism provides a means of connecting the biological and ecological features of virioplankton populations.
authors.affiliation: Department of Biological Sciences.
authors.forename: Eric G
authors.initials: EG
authors.lastname: Sakowski
authors.affiliation: Department of Chemical and Biomolecular Engineering.
authors.forename: Erik V
authors.initials: EV
authors.lastname: Munsell
authors.affiliation: Department of Biological Sciences.
authors.forename: Mara
authors.initials: M
authors.lastname: Hyatt
authors.affiliation: Department of Civil and Environmental Engineering, and.
authors.forename: William
authors.initials: W
authors.lastname: Kress
authors.affiliation: Lake Pend Oreille Waterkeeper, Sandpoint, ID 83864;
authors.forename: Shannon J
authors.initials: SJ
authors.lastname: Williamson
authors.affiliation: Center for Bioinformatics and Computational Biology, Delaware Biotechnology Institute, University of Delaware, Newark, DE 19716;
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Nasko
authors.affiliation: Department of Biological Sciences, Center for Bioinformatics and Computational Biology, Delaware Biotechnology Institute, University of Delaware, Newark, DE 19716; Department of Computer and Information Sciences, University of Delaware, Newark, DE 19716; Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711.
authors.forename: Shawn W
authors.initials: SW
authors.lastname: Polson
authors.affiliation: Department of Biological Sciences, Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711 Department of Plant and Soil Sciences and College of Earth, Ocean, and Environment, University of Delaware, Newark, DE 19716; and wommack@dbi.udel.edu.
authors.forename: K Eric
authors.initials: KE
authors.lastname: Wommack
mesh_terms: D059001:Aquatic Organisms / Q000235:genetics*; D001483:Base Sequence; D044822:Biodiversity; D004267:DNA Viruses / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D016679:Genome, Viral; D054892:Metagenome; D008969:Molecular Sequence Data; D012264:Ribonucleotide Reductases / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D014764:Viral Proteins; D012264:Ribonucleotide Reductases
keywords: phage replication; viral ecology; viral evolution