51
|
Claverie JM. Fundamental Difficulties Prevent the Reconstruction of the Deep Phylogeny of Viruses. Viruses 2020; 12:E1130. [PMID: 33036160 PMCID: PMC7600955 DOI: 10.3390/v12101130] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/01/2020] [Accepted: 10/03/2020] [Indexed: 12/11/2022] Open
Abstract
The extension of virology beyond its traditional medical, veterinary, or agricultural applications, now called environmental virology, has shown that viruses are both the most numerous and diverse biological entities on Earth. In particular, virus isolations from unicellular eukaryotic hosts (heterotrophic and photosynthetic protozoans) revealed numerous viral types previously unexpected in terms of virion structure, gene content, or mode of replication. Complemented by large-scale metagenomic analyses, these discoveries have rekindled interest in the enigma of the origin of viruses, for which a description encompassing all their diversity remains not available. Several laboratories have repeatedly tackled the deep reconstruction of the evolutionary history of viruses, using various methods of molecular phylogeny applied to the few shared "core" genes detected in certain virus groups (e.g., the Nucleocytoviricota). Beyond the practical difficulties of establishing reliable homology relationships from extremely divergent sequences, I present here conceptual arguments highlighting several fundamental limitations plaguing the reconstruction of the deep evolutionary history of viruses, and even more the identification of their unique or multiple origin(s). These arguments also underline the risk of establishing premature high level viral taxonomic classifications. Those limitations are direct consequences of the random mechanisms governing the reductive/retrogressive evolution of all obligate intracellular parasites.
Collapse
Affiliation(s)
- Jean-Michel Claverie
- Structural & Genomic Information Laboratory (IGS, UMR 7256), Mediterranean Institute of Microbiology (FR3479), Aix-Marseille University and CNRS, 13288 Marseille, France
| |
Collapse
|
52
|
Monk CH, Zwezdaryk KJ. Host Mitochondrial Requirements of Cytomegalovirus Replication. CURRENT CLINICAL MICROBIOLOGY REPORTS 2020; 7:115-123. [PMID: 33816061 PMCID: PMC8015347 DOI: 10.1007/s40588-020-00153-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Purpose of Review Metabolic rewiring of the host cell is required for optimal viral replication. Human cytomegalovirus (HCMV) has been observed to manipulate numerous mitochondrial functions. In this review, we describe the strategies and targets HCMV uses to control different aspects of mitochondrial function. Recent Findings The mitochondria are instrumental in meeting the biosynthetic and bioenergetic needs of HCMV replication. This is achieved through altered metabolism and signaling pathways. Morphological changes mediated through biogenesis and fission/fusion dynamics contribute to strategies to avoid cell death, overcome oxidative stress, and maximize the biosynthetic and bioenergetic outputs of mitochondria. Summary Emerging data suggests that cytomegalovirus relies on intact, functional host mitochondria for optimal replication. HCMV large size and slow replication kinetics create a dependency on mitochondria during replication. Targeting the host mitochondria is an attractive antiviral target.
Collapse
Affiliation(s)
- Chandler H Monk
- Department of Microbiology & Immunology, Tulane University Health Sciences Center, 1430 Tulane Ave #8638, New Orleans, LA 70112, USA
| | - Kevin J Zwezdaryk
- Department of Microbiology & Immunology, Tulane University Health Sciences Center, 1430 Tulane Ave #8638, New Orleans, LA 70112, USA
| |
Collapse
|
53
|
Fuchsman CA, Carlson MCG, Garcia Prieto D, Hays MD, Rocap G. Cyanophage host-derived genes reflect contrasting selective pressures with depth in the oxic and anoxic water column of the Eastern Tropical North Pacific. Environ Microbiol 2020; 23:2782-2800. [PMID: 32869473 DOI: 10.1111/1462-2920.15219] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 08/14/2020] [Accepted: 08/27/2020] [Indexed: 01/19/2023]
Abstract
Cyanophages encode host-derived genes that may increase their fitness. We examined the relative abundance of 18 host-derived cyanophages genes in metagenomes and viromes along depth profiles from the Eastern Tropical North Pacific Oxygen Deficient Zone (ETNP ODZ) where Prochlorococcus dominates a secondary chlorophyll maximum within the ODZ. Cyanophages at the oxic primary chlorophyll maximum encoded genes related to light and phosphate stress (psbA, psbD and pstS in T4-like and psbA in T7-like), but the proportion of cyanophage with these genes decreased with depth. The proportion of cyanophage with purine biosynthesis genes increased with depth in T4-like, but not T7-like cyanophages. No additional host-derived genes were found in deep T7-like cyanophages, suggesting that T4-like and T7-like cyanophages have different host-derived gene acquisition strategies, possibly linked to their different genome packaging mechanisms. In contrast to the ETNP, in the oxic North Atlantic T4-like cyanophages encoded psbA and pstS throughout the euphotic zone. Differences in pstS between the ETNP and the North Atlantic stations were consistent with differences in phosphate concentrations in those regimes. We suggest that the low proportion of cyanophage with psbA within the ODZ reflects the stably stratified low-light conditions occupied by their hosts, a Prochlorococcus ecotype endemic to ODZs.
Collapse
Affiliation(s)
- Clara A Fuchsman
- School of Oceanography, University of Washington, Seattle, WA, USA.,Horn Point Laboratory, University of Maryland Center of Environmental Science, Cambridge, MD, 21613, USA
| | - Michael C G Carlson
- School of Oceanography, University of Washington, Seattle, WA, USA.,Technion-Israel Institute of Technology, Haifa, Israel
| | - David Garcia Prieto
- School of Oceanography, University of Washington, Seattle, WA, USA.,Horn Point Laboratory, University of Maryland Center of Environmental Science, Cambridge, MD, 21613, USA
| | - Matthew D Hays
- Horn Point Laboratory, University of Maryland Center of Environmental Science, Cambridge, MD, 21613, USA
| | - Gabrielle Rocap
- School of Oceanography, University of Washington, Seattle, WA, USA
| |
Collapse
|
54
|
Thermodynamic insight into viral infections 2: empirical formulas, molecular compositions and thermodynamic properties of SARS, MERS and SARS-CoV-2 (COVID-19) viruses. Heliyon 2020; 6:e04943. [PMID: 32954038 PMCID: PMC7489929 DOI: 10.1016/j.heliyon.2020.e04943] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/03/2020] [Accepted: 09/11/2020] [Indexed: 12/17/2022] Open
Abstract
The current situation with the SARS-CoV-2 pandemic indicates the importance of new approaches in vaccine design. In order to design new attenuated vaccines, to decrease virulence of virus wild types, it is important to understand what allows a virus to hijack its host cell's metabolism, a property of all viruses. RNA and protein sequences obtained from databases were used to count the number of atoms of each element in the virions of SARS, MERS and SARS-CoV-2. The number of protein copies and carbohydrate composition were taken from the literature. The number of lipid molecules was estimated from the envelope surface area. Based on elemental composition, growth equations were balanced, and thermodynamic properties of the viruses were determined using Patel-Erickson and Battley equations. Elemental and molecular compositions of SARS, MERS and SARS-CoV-2 were found, as well as their standard thermodynamic properties of formation and growth. Standard Gibbs energy of growth of virus nucleocapsids was found to be significantly more negative than that of their host tissue. The ratio of Gibbs energies of growth of virus nucleocapsids and host cell is greater than unity. The more negative Gibbs energy of growth of viruses implies that virus multiplication has a greater driving force than synthesis of host cell components, giving a physical explanation of why viruses are able to hijack their host cell's metabolism. Knowing the mechanism of viral metabolism hijacking can open new paths for vaccine design. By manipulating chemical composition of viruses, virulence can be decreased by making the Gibbs energy of their growth less negative, resulting in decreased multiplication rate, while preserving antigenic properties.
Collapse
|
55
|
Song Y, Shvartsman SY. Chemical Embryology Redux: Metabolic Control of Development. Trends Genet 2020; 36:577-586. [PMID: 32532533 PMCID: PMC10947471 DOI: 10.1016/j.tig.2020.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/14/2020] [Accepted: 05/18/2020] [Indexed: 11/16/2022]
Abstract
New studies of metabolic reactions and networks in embryos are making important additions to regulatory models of development, so far dominated by genes and signals. Metabolic control of development is not a new idea and can be traced back to Joseph Needham's 'Chemical Embryology', published in the 1930s. Even though Needham's ideas fell by the wayside with the advent of genetic studies of embryogenesis, they demonstrated that embryos provide convenient models for addressing fundamental questions in biochemistry and are now experiencing a comeback, enabled by the powerful merger of detailed mechanistic studies and systems-level techniques. Here we review recent results from studies that quantified the energy budget of embryogenesis in Drosophila and started to untangle the intricate connections between core anabolic processes and developmental transitions. Dynamic coordination of metabolic, genetic, and signaling networks appears to be essential for seamless progression of development.
Collapse
Affiliation(s)
- Yonghyun Song
- Computational Sciences Department, Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
| | - Stanislav Y Shvartsman
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Center for Computational Biology, Flatiron Institute - Simons Foundation, New York, NY 10010, USA.
| |
Collapse
|
56
|
Selection for Reducing Energy Cost of Protein Production Drives the GC Content and Amino Acid Composition Bias in Gene Transfer Agents. mBio 2020; 11:mBio.01206-20. [PMID: 32665274 PMCID: PMC7360931 DOI: 10.1128/mbio.01206-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Kin selection and group selection remain controversial topics in evolutionary biology. We argue that these types of selection are likely to operate in bacterial populations by showing that bacterial gene transfer agents (GTAs), but not related viruses, evolve under conditions of positive selection for the reduction of the energy cost of GTA particle production. We hypothesize that GTAs are dedicated devices mediating the survival of bacteria under conditions of nutrient limitation. The benefits conferred by GTAs under nutritional stress conditions appear to include horizontal dissemination of genes that could provide bacteria with enhanced capabilities for nutrient utilization and increases of nutrient availability occurring through the lysis of GTA-producing bacteria. Gene transfer agents (GTAs) are virus-like elements integrated into bacterial genomes, particularly, those of Alphaproteobacteria. The GTAs can be induced under conditions of nutritional stress, incorporate random fragments of bacterial DNA into miniphage particles, lyse the host cells, and infect neighboring bacteria, thus enhancing horizontal gene transfer. We show that GTA genes evolve under conditions of pronounced positive selection for the reduction of the energy cost of protein production as shown by comparison of the amino acid compositions with those of both homologous viral genes and host genes. The energy saving in GTA genes is comparable to or even more pronounced than that in the genes encoding the most abundant, essential bacterial proteins. In cases in which viruses acquire genes from GTAs, the bias in amino acid composition disappears in the course of evolution, showing that reduction of the energy cost of protein production is an important factor of evolution of GTAs but not bacterial viruses. These findings strongly suggest that GTAs represent bacterial adaptations rather than selfish, virus-like elements. Because GTA production kills the host cell and does not propagate the GTA genome, it appears likely that the GTAs are retained in the course of evolution via kin or group selection. Therefore, we hypothesize that GTAs facilitate the survival of bacterial populations under energy-limiting conditions through the spread of metabolic and transport capabilities via horizontal gene transfer and increases in nutrient availability resulting from the altruistic suicide of GTA-producing cells.
Collapse
|
57
|
A thermodynamic insight into viral infections: do viruses in a lytic cycle hijack cell metabolism due to their low Gibbs energy? Heliyon 2020; 6:e03933. [PMID: 32420495 PMCID: PMC7218021 DOI: 10.1016/j.heliyon.2020.e03933] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 03/02/2020] [Accepted: 05/01/2020] [Indexed: 12/22/2022] Open
Abstract
After adsorption and penetration, a virus hijacks a cell's metabolic machinery and uses it as a medium for its reproduction and growth through multiplication. Growth is competitive, since the same precursors and machinery are used by both the virus and its host cell. But what drives a virus to perform its life cycle more efficiently than its host? Gibbs energy represents the driving force for all chemical reactions in nature. Therefore, hypothetically Gibbs energy of growth can represent the driving force of viral lytic cycle. After chemical characterization of 17 viruses and their hosts, in this paper, growth reactions were suggested, and enthalpy, entropy and Gibbs free energy of both formation and growth were calculated. By comparing the Gibbs energy of growth of viruses and their hosts, it has been found that a virus always has a more negative Gibbs free energy of growth than its host implying that synthesis of viral components is more thermodynamically favorable. Thus, it seems that the physical laws explain observed biological phenomena - the hijack of host life machinery and high efficiency of virus growth.
Collapse
|
58
|
Coming-of-Age Characterization of Soil Viruses: A User’s Guide to Virus Isolation, Detection within Metagenomes, and Viromics. SOIL SYSTEMS 2020. [DOI: 10.3390/soilsystems4020023] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The study of soil viruses, though not new, has languished relative to the study of marine viruses. This is particularly due to challenges associated with separating virions from harboring soils. Generally, three approaches to analyzing soil viruses have been employed: (1) Isolation, to characterize virus genotypes and phenotypes, the primary method used prior to the start of the 21st century. (2) Metagenomics, which has revealed a vast diversity of viruses while also allowing insights into viral community ecology, although with limitations due to DNA from cellular organisms obscuring viral DNA. (3) Viromics (targeted metagenomics of virus-like-particles), which has provided a more focused development of ‘virus-sequence-to-ecology’ pipelines, a result of separation of presumptive virions from cellular organisms prior to DNA extraction. This separation permits greater sequencing emphasis on virus DNA and thereby more targeted molecular and ecological characterization of viruses. Employing viromics to characterize soil systems presents new challenges, however. Ones that only recently are being addressed. Here we provide a guide to implementing these three approaches to studying environmental viruses, highlighting benefits, difficulties, and potential contamination, all toward fostering greater focus on viruses in the study of soil ecology.
Collapse
|
59
|
Howard-Varona C, Lindback MM, Bastien GE, Solonenko N, Zayed AA, Jang H, Andreopoulos B, Brewer HM, Glavina Del Rio T, Adkins JN, Paul S, Sullivan MB, Duhaime MB. Phage-specific metabolic reprogramming of virocells. ISME JOURNAL 2020; 14:881-895. [PMID: 31896786 PMCID: PMC7082346 DOI: 10.1038/s41396-019-0580-z] [Citation(s) in RCA: 111] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/25/2019] [Accepted: 12/17/2019] [Indexed: 12/22/2022]
Abstract
Ocean viruses are abundant and infect 20–40% of surface microbes. Infected cells, termed virocells, are thus a predominant microbial state. Yet, virocells and their ecosystem impacts are understudied, thus precluding their incorporation into ecosystem models. Here we investigated how unrelated bacterial viruses (phages) reprogram one host into contrasting virocells with different potential ecosystem footprints. We independently infected the marine Pseudoalteromonas bacterium with siphovirus PSA-HS2 and podovirus PSA-HP1. Time-resolved multi-omics unveiled drastically different metabolic reprogramming and resource requirements by each virocell, which were related to phage–host genomic complementarity and viral fitness. Namely, HS2 was more complementary to the host in nucleotides and amino acids, and fitter during infection than HP1. Functionally, HS2 virocells hardly differed from uninfected cells, with minimal host metabolism impacts. HS2 virocells repressed energy-consuming metabolisms, including motility and translation. Contrastingly, HP1 virocells substantially differed from uninfected cells. They repressed host transcription, responded to infection continuously, and drastically reprogrammed resource acquisition, central carbon and energy metabolisms. Ecologically, this work suggests that one cell, infected versus uninfected, can have immensely different metabolisms that affect the ecosystem differently. Finally, we relate phage–host genome complementarity, virocell metabolic reprogramming, and viral fitness in a conceptual model to guide incorporating viruses into ecosystem models.
Collapse
Affiliation(s)
- Cristina Howard-Varona
- Department of Microbiology, The Ohio State University, 484 W 12th Ave, Columbus, OH, 43210, USA
| | - Morgan M Lindback
- Department of Ecology and Evolutionary Biology, University of Michigan, 1105 North University Ave, Ann Arbor, MI, 48109, USA
| | - G Eric Bastien
- Department of Ecology and Evolutionary Biology, University of Michigan, 1105 North University Ave, Ann Arbor, MI, 48109, USA
| | - Natalie Solonenko
- Department of Microbiology, The Ohio State University, 484 W 12th Ave, Columbus, OH, 43210, USA
| | - Ahmed A Zayed
- Department of Microbiology, The Ohio State University, 484 W 12th Ave, Columbus, OH, 43210, USA
| | - HoBin Jang
- Department of Microbiology, The Ohio State University, 484 W 12th Ave, Columbus, OH, 43210, USA
| | - Bill Andreopoulos
- US Department of Energy Joint Genome Institute, 1800 Mitchell Dr #100, Walnut Creek, CA, 94598, USA
| | - Heather M Brewer
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory (PNNL), 902 Battelle Blvd, Richland, WA, 99354, USA
| | - Tijana Glavina Del Rio
- US Department of Energy Joint Genome Institute, 1800 Mitchell Dr #100, Walnut Creek, CA, 94598, USA
| | - Joshua N Adkins
- Biological Science Division, PNNL, 902 Battelle Blvd, Richland, WA, 99354, USA
| | - Subhadeep Paul
- Department of Statistics, The Ohio State University, 1958 Neil Ave, Columbus, OH, 43210, USA
| | - Matthew B Sullivan
- Department of Microbiology, The Ohio State University, 484 W 12th Ave, Columbus, OH, 43210, USA. .,Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, 2070 Neil Ave, Columbus, OH, 43210, USA. .,Center for RNA Biology, The Ohio State University, 484 W. 12th Ave, Columbus, OH, 43210, USA.
| | - Melissa B Duhaime
- Department of Ecology and Evolutionary Biology, University of Michigan, 1105 North University Ave, Ann Arbor, MI, 48109, USA.
| |
Collapse
|
60
|
Chevallereau A, Meaden S, Fradet O, Landsberger M, Maestri A, Biswas A, Gandon S, van Houte S, Westra ER. Exploitation of the Cooperative Behaviors of Anti-CRISPR Phages. Cell Host Microbe 2019; 27:189-198.e6. [PMID: 31901522 PMCID: PMC7013381 DOI: 10.1016/j.chom.2019.12.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/13/2019] [Accepted: 12/06/2019] [Indexed: 12/14/2022]
Abstract
Bacteriophages encoding anti-CRISPR proteins (Acrs) must cooperate to overcome phage resistance mediated by the bacterial immune system CRISPR-Cas, where the first phage blocks CRISPR-Cas immunity in order to allow a second Acr phage to successfully replicate. However, in nature, bacteria are frequently not pre-immunized, and phage populations are often not clonal, exhibiting variations in Acr presence and strength. We explored how interactions between Acr phages and initially sensitive bacteria evolve, both in the presence and absence of competing phages lacking Acrs. We find that Acr phages benefit “Acr-negative” phages by limiting the evolution of CRISPR-based resistance and helping Acr-negative phages to replicate on resistant host sub-populations. These benefits depend on the strength of CRISPR-Cas inhibitors and result in strong Acrs providing smaller fitness advantages than weaker ones when Acr phages compete with Acr-negative phages. These results indicate that different Acr types shape the evolutionary dynamics and social interactions of phage populations in natural communities. Acr-positive phages limit evolution of CRISPR resistance during clonal and mixed infections Acr-positive phages provide benefits to Acr-negative phages present in the community Strong Acr help Acr-negative phages to amplify on immunosuppressed CRISPR-resistant cells Weaker Acr provides larger advantages during competition with Acr-negative phages
Collapse
Affiliation(s)
- Anne Chevallereau
- ESI, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK.
| | - Sean Meaden
- ESI, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK
| | - Olivier Fradet
- ESI, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK
| | - Mariann Landsberger
- ESI, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK
| | - Alice Maestri
- ESI, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK
| | - Ambarish Biswas
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Sylvain Gandon
- CEFE, Université de Montpellier, CNRS, EPHE, IRD, Université Paul Valéry Montpellier 3, Montpellier, France
| | - Stineke van Houte
- ESI, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK
| | - Edze R Westra
- ESI, Biosciences, University of Exeter, Cornwall Campus, Penryn TR10 9EZ, UK.
| |
Collapse
|
61
|
Wang X, Lin Y, Kemper T, Chen J, Yuan Z, Liu S, Zhu Y, Broering R, Lu M. AMPK and Akt/mTOR signalling pathways participate in glucose-mediated regulation of hepatitis B virus replication and cellular autophagy. Cell Microbiol 2019; 22:e13131. [PMID: 31746509 DOI: 10.1111/cmi.13131] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/06/2019] [Accepted: 10/17/2019] [Indexed: 12/13/2022]
Abstract
A growing consensus indicates that host metabolism plays a vital role in viral infections. Hepatitis B virus (HBV) infection occurs in hepatocytes with active glucose metabolism and may be regulated by cellular metabolism. We addressed the question whether and how glucose regulates HBV replication in hepatocytes. The low glucose concentration at 5 mM significantly promoted HBV replication via enhanced transcription and autophagy when compared with higher glucose concentrations (10 and 25 mM). At low glucose concentration, AMPK activity was increased and led to ULK1 phosphorylation at Ser 555 and LC3-II accumulation. By contrast, the mTOR pathway was activated by high glucose concentrations, resulting in reduced HBV replication. mTOR inhibition by rapamycin reversed negative effects of high glucose concentrations on HBV replication, suggesting that low glucose concentration promotes HBV replication by stimulating the AMPK/mTOR-ULK1-autophagy axis. Consistently, we found that glucose transporters inhibition using phloretin also enhanced HBV replication via increased AMPK/mTOR-ULK1-induced autophagy. Surprisingly, the glucose analogue 2-deoxy-D-glucose reduced HBV replication through activating the Akt/mTOR signalling pathway also at the low glucose concentrations. Our study reveals that glucose is an important factor for the HBV life cycle by regulating HBV transcription and posttranscriptional steps of HBV replication via cellular autophagy.
Collapse
Affiliation(s)
- Xueyu Wang
- Institute of Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Yong Lin
- Institute of Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Thekla Kemper
- Institute of Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Jieliang Chen
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Medical College, Fudan University, Shanghai, China
| | - Zhenghong Yuan
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Medical College, Fudan University, Shanghai, China
| | - Shi Liu
- Institute of Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.,State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Ying Zhu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Ruth Broering
- Department of Gastroenterology and Hepatology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Mengji Lu
- Institute of Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| |
Collapse
|
62
|
Zimmerman AE, Howard-Varona C, Needham DM, John SG, Worden AZ, Sullivan MB, Waldbauer JR, Coleman ML. Metabolic and biogeochemical consequences of viral infection in aquatic ecosystems. Nat Rev Microbiol 2019; 18:21-34. [PMID: 31690825 DOI: 10.1038/s41579-019-0270-x] [Citation(s) in RCA: 168] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2019] [Indexed: 12/23/2022]
Abstract
Ecosystems are controlled by 'bottom-up' (resources) and 'top-down' (predation) forces. Viral infection is now recognized as a ubiquitous top-down control of microbial growth across ecosystems but, at the same time, cell death by viral predation influences, and is influenced by, resource availability. In this Review, we discuss recent advances in understanding the biogeochemical impact of viruses, focusing on how metabolic reprogramming of host cells during lytic viral infection alters the flow of energy and nutrients in aquatic ecosystems. Our synthesis revealed several emerging themes. First, viral infection transforms host metabolism, in part through virus-encoded metabolic genes; the functions performed by these genes appear to alleviate energetic and biosynthetic bottlenecks to viral production. Second, viral infection depends on the physiological state of the host cell and on environmental conditions, which are challenging to replicate in the laboratory. Last, metabolic reprogramming of infected cells and viral lysis alter nutrient cycling and carbon export in the oceans, although the net impacts remain uncertain. This Review highlights the need for understanding viral infection dynamics in realistic physiological and environmental contexts to better predict their biogeochemical consequences.
Collapse
Affiliation(s)
- Amy E Zimmerman
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
| | | | - David M Needham
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA
| | - Seth G John
- Department of Earth Science, University of Southern California, Los Angeles, CA, USA
| | - Alexandra Z Worden
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA.,Ocean EcoSystems Biology Unit, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Matthew B Sullivan
- Department of Microbiology, Ohio State University, Columbus, OH, USA.,Department of Civil, Environmental and Geodetic Engineering, Ohio State University, Columbus, OH, USA
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
| | - Maureen L Coleman
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA.
| |
Collapse
|
63
|
Metabolic perturbations and cellular stress underpin susceptibility to symptomatic live-attenuated yellow fever infection. Nat Med 2019; 25:1218-1224. [PMID: 31308506 DOI: 10.1038/s41591-019-0510-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 05/20/2019] [Indexed: 12/19/2022]
Abstract
Flaviviral infections result in a wide spectrum of clinical outcomes, ranging from asymptomatic infection to severe disease. Although the correlates of severe disease have been explored1-4, the pathophysiology that differentiates symptomatic from asymptomatic infection remains undefined. To understand the molecular underpinnings of symptomatic infection, the blood transcriptomic and metabolomic profiles of individuals were examined before and after inoculation with the live yellow fever viral vaccine (YF17D). It was found that individuals with adaptive endoplasmic reticulum (ER) stress and reduced tricarboxylic acid cycle activity at baseline showed increased susceptibility to symptomatic outcome. YF17D infection in these individuals induced maladaptive ER stress, triggering downstream proinflammatory responses that correlated with symptomatic outcome. The findings of the present study thus suggest that the ER stress response and immunometabolism underpin symptomatic yellow fever and possibly even other flaviviral infections. Modulating either ER stress or metabolism could be exploited for prophylaxis against symptomatic flaviviral infection outcome.
Collapse
|
64
|
Ilker E, Hinczewski M. Modeling the Growth of Organisms Validates a General Relation between Metabolic Costs and Natural Selection. PHYSICAL REVIEW LETTERS 2019; 122:238101. [PMID: 31298905 DOI: 10.1103/physrevlett.122.238101] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 11/11/2018] [Indexed: 06/10/2023]
Abstract
Metabolism and evolution are closely connected: if a mutation incurs extra energetic costs for an organism, there is a baseline selective disadvantage that may or may not be compensated for by other adaptive effects. A long-standing, but to date unproven, hypothesis is that this disadvantage is equal to the fractional cost relative to the total resting metabolic expenditure. We validate this result from physical principles through a general growth model and show it holds to excellent approximation for experimental parameters drawn from a wide range of species.
Collapse
Affiliation(s)
- Efe Ilker
- Physico-Chimie Curie UMR 168, Institut Curie, PSL Research University, 26 rue d'Ulm, 75248 Paris Cedex 05, France
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Michael Hinczewski
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA
| |
Collapse
|
65
|
Zimmerman AE, Bachy C, Ma X, Roux S, Jang HB, Sullivan MB, Waldbauer JR, Worden AZ. Closely related viruses of the marine picoeukaryotic alga Ostreococcus lucimarinus exhibit different ecological strategies. Environ Microbiol 2019; 21:2148-2170. [PMID: 30924271 PMCID: PMC6851583 DOI: 10.1111/1462-2920.14608] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 03/16/2019] [Accepted: 03/23/2019] [Indexed: 01/01/2023]
Abstract
In marine ecosystems, viruses are major disrupters of the direct flow of carbon and nutrients to higher trophic levels. Although the genetic diversity of several eukaryotic phytoplankton virus groups has been characterized, their infection dynamics are less understood, such that the physiological and ecological implications of their diversity remain unclear. We compared genomes and infection phenotypes of the two most closely related cultured phycodnaviruses infecting the widespread picoprasinophyte Ostreococcus lucimarinus under standard- (1.3 divisions per day) and limited-light (0.41 divisions per day) nutrient replete conditions. OlV7 infection caused early arrest of the host cell cycle, coinciding with a significantly higher proportion of infected cells than OlV1-amended treatments, regardless of host growth rate. OlV7 treatments showed a near-50-fold increase of progeny virions at the higher host growth rate, contrasting with OlV1's 16-fold increase. However, production of OlV7 virions was more sensitive than OlV1 production to reduced host growth rate, suggesting fitness trade-offs between infection efficiency and resilience to host physiology. Moreover, although organic matter released from OlV1- and OlV7-infected hosts had broadly similar chemical composition, some distinct molecular signatures were observed. Collectively, these results suggest that current views on viral relatedness through marker and core gene analyses underplay operational divergence and consequences for host ecology.
Collapse
Affiliation(s)
| | - Charles Bachy
- Monterey Bay Aquarium Research InstituteMoss LandingCAUSA
| | - Xiufeng Ma
- Department of the Geophysical SciencesUniversity of ChicagoChicagoILUSA
| | - Simon Roux
- Department of MicrobiologyEnvironmental and Geodetic Engineering, The Ohio State UniversityColumbusOHUSA
| | - Ho Bin Jang
- Department of MicrobiologyEnvironmental and Geodetic Engineering, The Ohio State UniversityColumbusOHUSA
- Department of CivilEnvironmental and Geodetic Engineering, The Ohio State UniversityColumbusOHUSA
| | - Matthew B. Sullivan
- Department of MicrobiologyEnvironmental and Geodetic Engineering, The Ohio State UniversityColumbusOHUSA
- Department of CivilEnvironmental and Geodetic Engineering, The Ohio State UniversityColumbusOHUSA
| | | | - Alexandra Z. Worden
- Monterey Bay Aquarium Research InstituteMoss LandingCAUSA
- Ocean EcoSystems Biology Unit, Marine Ecology DivisionGEOMAR Helmholtz Centre for Ocean Research KielKielDE
| |
Collapse
|
66
|
Laske T, Bachmann M, Dostert M, Karlas A, Wirth D, Frensing T, Meyer TF, Hauser H, Reichl U. Model-based analysis of influenza A virus replication in genetically engineered cell lines elucidates the impact of host cell factors on key kinetic parameters of virus growth. PLoS Comput Biol 2019; 15:e1006944. [PMID: 30973879 PMCID: PMC6478349 DOI: 10.1371/journal.pcbi.1006944] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 04/23/2019] [Accepted: 03/11/2019] [Indexed: 12/25/2022] Open
Abstract
The best measure to limit spread of contagious diseases caused by influenza A viruses (IAVs) is annual vaccination. The growing global demand for low-cost vaccines requires the establishment of high-yield production processes. One possible option to address this challenge is the engineering of novel vaccine producer cell lines by manipulating gene expression of host cell factors relevant for virus replication. To support detailed characterization of engineered cell lines, we fitted an ordinary differential equation (ODE)-based model of intracellular IAV replication previously established by our group to experimental data obtained from infection studies in human A549 cells. Model predictions indicate that steps of viral RNA synthesis, their regulation and particle assembly and virus budding are promising targets for cell line engineering. The importance of these steps was confirmed in four of five single gene overexpression cell lines (SGOs) that showed small, but reproducible changes in early dynamics of RNA synthesis and virus release. Model-based analysis suggests, however, that overexpression of the selected host cell factors negatively influences specific RNA synthesis rates. Still, virus yield was rescued by an increase in the virus release rate. Based on parameter estimations obtained for SGOs, we predicted that there is a potential benefit associated with overexpressing multiple host cell genes in one cell line, which was validated experimentally. Overall, this model-based study on IAV replication in engineered cell lines provides a step forward in the dynamic and quantitative characterization of IAV-host cell interactions. Furthermore, it suggests targets for gene editing and indicates that overexpression of multiple host cell factors may be beneficial for the design of novel producer cell lines.
Collapse
Affiliation(s)
- Tanja Laske
- Department of Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Mandy Bachmann
- Department of Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Melanie Dostert
- Department of Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Alexander Karlas
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Dagmar Wirth
- Research Group Model Systems for Infection and Immunity, Helmholtz Center for Infection Research, Braunschweig, Germany
- Division of Experimental Hematology, Medical University Hannover, Hannover, Germany
| | - Timo Frensing
- Department of Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Thomas F. Meyer
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Hansjörg Hauser
- Department of Gene Regulation and Differentiation, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Udo Reichl
- Department of Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
- Chair of Bioprocess Engineering, Faculty of Process and Systems Engineering, Otto von Guericke University, Magdeburg, Germany
| |
Collapse
|
67
|
Xu J, Kiesel B, Kallies R, Jiang F, Liu Y, Maskow T. A fast and reliable method for monitoring of prophage-activating chemicals. Microb Biotechnol 2018; 11:1112-1120. [PMID: 29327434 PMCID: PMC6196395 DOI: 10.1111/1751-7915.13042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/17/2017] [Accepted: 11/27/2017] [Indexed: 12/03/2022] Open
Abstract
Bacteriophages, that is viruses that infect bacteria, either lyse bacteria directly or integrate their genome into the bacterial genome as so-called prophages, where they remain at a silent state. Both phages and bacteria are able to survive in this state. However, prophages can be reactivated with the introduction of chemicals, followed by the release of a high number of phage particles, which could infect other bacteria, thus harming ecosystems by a viral bloom. The basics for a fast, automatable analytical method for the detection of prophage-activating chemicals are developed and successfully tested here. The method exploits the differences in metabolic heat produced by Escherichia coli with (λ+) and without the lambda prophages (λ-). Since the metabolic heat primarily reflects opposing effects (i.e. the reduction of heat-producing cells by lysis and enhanced heat production to deliver the energetic costs for the synthesis of phages), a systematic analysis of the influence of the different conditions (experimentally and in silico) was performed and revealed anoxic conditions to be best suited. The main advantages of the suggested monitoring method are not only the possibility of obtaining fast results (after only few hours), but also the option for automation, the low workload (requires only few minutes) and the suitability of using commercially available instruments. The future challenge following this proof of principle is the development of thermal transducers which allow for the electronic subtraction of the λ+ from the λ- signal.
Collapse
Affiliation(s)
- Juan Xu
- State Key Laboratory of VirologyCollege of Chemistry and Molecule SciencesWuhan UniversityWuhan430072China
| | - Bärbel Kiesel
- Department of Environmental MicrobiologyUFZ – Helmholtz Centre for Environmental ResearchPermoserstrasse 1504318LeipzigGermany
| | - René Kallies
- Department of Environmental MicrobiologyUFZ – Helmholtz Centre for Environmental ResearchPermoserstrasse 1504318LeipzigGermany
| | - Feng‐Lei Jiang
- State Key Laboratory of VirologyCollege of Chemistry and Molecule SciencesWuhan UniversityWuhan430072China
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)College of Chemistry and Molecule SciencesWuhan UniversityWuhan430072China
| | - Yi Liu
- State Key Laboratory of VirologyCollege of Chemistry and Molecule SciencesWuhan UniversityWuhan430072China
- Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education)College of Chemistry and Molecule SciencesWuhan UniversityWuhan430072China
| | - Thomas Maskow
- Department of Environmental MicrobiologyUFZ – Helmholtz Centre for Environmental ResearchPermoserstrasse 1504318LeipzigGermany
| |
Collapse
|
68
|
Qu C, Zhang S, Wang W, Li M, Wang Y, van der Heijde-Mulder M, Shokrollahi E, Hakim MS, Raat NJH, Peppelenbosch MP, Pan Q. Mitochondrial electron transport chain complex III sustains hepatitis E virus replication and represents an antiviral target. FASEB J 2018; 33:1008-1019. [PMID: 30070932 DOI: 10.1096/fj.201800620r] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hepatitis E virus (HEV) infection has emerged as a global health problem. However, no approved medication is available, and the infection biology remains largely elusive. Electron transport chain (ETC), a key component of the mitochondria, is the main site that produces ATP and reactive oxygen species (ROS). By profiling the role of the different complexes of the mitochondrial ETC, we found that pharmacological inhibition of complex III, a well-defined drug target for the treatment of malaria and Pneumocystis pneumonia, potently restricts HEV replication. This effect demonstrated in our HEV models is equivalent to the anti-HEV potency of ribavirin, a widely used off-label treatment for patients with chronic HEV. Mechanistically, we found that this effect is independent of ATP production, ROS level, and pyridine depletion. By using pharmacological inhibitors and genetic approaches, we found that mitochondrial permeability transition pore (MPTP), a newly identified component of ETC, provides basal defense against HEV infection. HEV interferes with the opening of the MPTP. Furthermore, inhibition of the MPTP attenuated the anti-HEV effect of complex III inhibitors, suggesting that the MPTP mediates the antiviral effects of these inhibitors. These findings reveal new insights on HEV-host interactions and provide viable anti-HEV targets for therapeutic development.-Qu, C., Zhang, S., Wang, W., Li, M., Wang, Y., van der Heijde-Mulder, M., Shokrollahi, E., Hakim, M. S., Raat, N. J. H., Peppelenbosch, M. P., Pan, Q. Mitochondrial electron transport chain complex III sustains hepatitis E virus replication and represents an antiviral target.
Collapse
Affiliation(s)
- Changbo Qu
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Shaoshi Zhang
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Wenshi Wang
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Meng Li
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Yijin Wang
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands.,Department of Pathology and Hepatology, Beijing 302 Hospital, Beijing, China
| | | | - Ehsan Shokrollahi
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, The Erasmus University Medical Center (Erasmus MC), Rotterdam, The Netherlands; and
| | - Mohamad S Hakim
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands.,Department of Microbiology, Faculty of Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Nicolaas J H Raat
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, The Erasmus University Medical Center (Erasmus MC), Rotterdam, The Netherlands; and
| | - Maikel P Peppelenbosch
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| | - Qiuwei Pan
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands
| |
Collapse
|
69
|
Abstract
When a virus infects a host cell, it hijacks the biosynthetic capacity of the cell to produce virus progeny, a process that may take less than an hour or more than a week. The overall time required for a virus to reproduce depends collectively on the rates of multiple steps in the infection process, including initial binding of the virus particle to the surface of the cell, virus internalization and release of the viral genome within the cell, decoding of the genome to make viral proteins, replication of the genome, assembly of progeny virus particles, and release of these particles into the extracellular environment. For a large number of virus types, much has been learned about the molecular mechanisms and rates of the various steps. However, in only relatively few cases during the last 50 years has an attempt been made-using mathematical modeling-to account for how the different steps contribute to the overall timing and productivity of the infection cycle in a cell. Here we review the initial case studies, which include studies of the one-step growth behavior of viruses that infect bacteria (Qβ, T7, and M13), human immunodeficiency virus, influenza A virus, poliovirus, vesicular stomatitis virus, baculovirus, hepatitis B and C viruses, and herpes simplex virus. Further, we consider how such models enable one to explore how cellular resources are utilized and how antiviral strategies might be designed to resist escape. Finally, we highlight challenges and opportunities at the frontiers of cell-level modeling of virus infections.
Collapse
Affiliation(s)
- John Yin
- Department of Chemical and Biological Engineering, Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jacob Redovich
- Department of Chemical and Biological Engineering, Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin, USA
| |
Collapse
|
70
|
Conrad SJ, Silva RF, Hearn CJ, Climans M, Dunn JR. Attenuation of Marek's disease virus by codon pair deoptimization of a core gene. Virology 2018; 516:219-226. [DOI: 10.1016/j.virol.2018.01.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 01/05/2018] [Accepted: 01/25/2018] [Indexed: 12/24/2022]
|
71
|
Puxty RJ, Evans DJ, Millard AD, Scanlan DJ. Energy limitation of cyanophage development: implications for marine carbon cycling. ISME JOURNAL 2018; 12:1273-1286. [PMID: 29379179 PMCID: PMC5931967 DOI: 10.1038/s41396-017-0043-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/25/2017] [Accepted: 12/09/2017] [Indexed: 11/16/2022]
Abstract
Marine cyanobacteria are responsible for ~25% of the fixed carbon that enters the ocean biosphere. It is thought that abundant co-occurring viruses play an important role in regulating population dynamics of cyanobacteria and thus the cycling of carbon in the oceans. Despite this, little is known about how viral infections ‘play-out’ in the environment, particularly whether infections are resource or energy limited. Photoautotrophic organisms represent an ideal model to test this since available energy is modulated by the incoming light intensity through photophosphorylation. Therefore, we exploited phototrophy of the environmentally relevant marine cyanobacterium Synechococcus and monitored growth of a cyanobacterial virus (cyanophage). We found that light intensity has a marked effect on cyanophage infection dynamics, but that this is not manifest by a change in DNA synthesis. Instead, cyanophage development appears energy limited for the synthesis of proteins required during late infection. We posit that acquisition of auxiliary metabolic genes (AMGs) involved in light-dependent photosynthetic reactions acts to overcome this limitation. We show that cyanophages actively modulate expression of these AMGs in response to light intensity and provide evidence that such regulation may be facilitated by a novel mechanism involving light-dependent splicing of a group I intron in a photosynthetic AMG. Altogether, our data offers a mechanistic link between diurnal changes in irradiance and observed community level responses in metabolism, i.e., through an irradiance-dependent, viral-induced release of dissolved organic matter (DOM).
Collapse
Affiliation(s)
- Richard J Puxty
- School of Life Sciences, University of Warwick, Coventry, West Midlands, CV4 7AL, UK
| | - David J Evans
- School of Biology and BSRC, Biomolecular Sciences Building, North Haugh, St Andrews, KY16 9AJ, UK
| | - Andrew D Millard
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, LE1 9HNL, UK
| | - David J Scanlan
- School of Life Sciences, University of Warwick, Coventry, West Midlands, CV4 7AL, UK.
| |
Collapse
|