1
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Grim SL, Stuart DG, Aron P, Levin NE, Kinsman-Costello L, Waldbauer JR, Dick GJ. Seasonal shifts in community composition and proteome expression in a sulphur-cycling cyanobacterial mat. Environ Microbiol 2023; 25:2516-2533. [PMID: 37596970 DOI: 10.1111/1462-2920.16480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 07/29/2023] [Indexed: 08/21/2023]
Abstract
Seasonal changes in light and physicochemical conditions have strong impacts on cyanobacteria, but how they affect community structure, metabolism, and biogeochemistry of cyanobacterial mats remains unclear. Light may be particularly influential for cyanobacterial mats exposed to sulphide by altering the balance of oxygenic photosynthesis and sulphide-driven anoxygenic photosynthesis. We studied temporal shifts in irradiance, water chemistry, and community structure and function of microbial mats in the Middle Island Sinkhole (MIS), where anoxic and sulphate-rich groundwater provides habitat for cyanobacteria that conduct both oxygenic and anoxygenic photosynthesis. Seasonal changes in light and groundwater chemistry were accompanied by shifts in bacterial community composition, with a succession of dominant cyanobacteria from Phormidium to Planktothrix, and an increase in diatoms, sulphur-oxidizing bacteria, and sulphate-reducing bacteria from summer to autumn. Differential abundance of cyanobacterial light-harvesting proteins likely reflects a physiological response of cyanobacteria to light level. Beggiatoa sulphur oxidation proteins were more abundant in autumn. Correlated abundances of taxa through time suggest interactions between sulphur oxidizers and sulphate reducers, sulphate reducers and heterotrophs, and cyanobacteria and heterotrophs. These results support the conclusion that seasonal change, including light availability, has a strong influence on community composition and biogeochemical cycling of sulphur and O2 in cyanobacterial mats.
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Affiliation(s)
- Sharon L Grim
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Dack G Stuart
- Cooperative Institute for Great Lakes Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Phoebe Aron
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Naomi E Levin
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - Gregory J Dick
- Department of Earth and Environmental Sciences, Cooperative Institute for Great Lakes Research, University of Michigan, Ann Arbor, Michigan, USA
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2
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Miller SE, Colman AS, Waldbauer JR. Metaproteomics reveals functional partitioning and vegetational variation among permafrost-affected Arctic soil bacterial communities. mSystems 2023:e0123822. [PMID: 37272710 DOI: 10.1128/msystems.01238-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023] Open
Abstract
Microbial activity in Arctic soils controls the cycling of significant stores of organic carbon and nutrients. We studied in situ processes in Alaskan soils using original metaproteomic methods in order to relate important heterotrophic functions to microbial taxa and to understand the microbial response to Arctic greening. Major bacterial groups show strong metabolic specialization in organic topsoils. α-/β-/γ-Proteobacteria specialized in the acquisition of small, soluble compounds, whereas Acidobacteria, Actinobacteria, and other detritosphere groups specialized in the degradation of plant-derived polymers. α-/β-/γ-Proteobacteria dominated the expression of transporters for common root exudates and limiting nitrogenous compounds, supporting an ecological model of dependence upon plants for carbon and competition with plants for nitrogen. Detritosphere groups specialized in distinct substrates, with Acidobacteria producing the most enzymes for hemicellulose depolymerization. Acidobacteria was the most active group across the three plant ecotypes sampled-the largely nonvascular, lower biomass intertussock and the largely vascular, higher biomass tussock and shrub. Functional partitioning among bacterial groups was stable between plant ecotypes, but certain functions associated with α-/β-/γ-Proteobacteria were more strongly expressed in higher biomass ecotypes. We show that refined metaproteomic approaches can elucidate soil microbial ecology as well as biogeochemical trajectories of major carbon stocks.IMPORTANCEThe Arctic is warming twice as fast as the rest of the planet, and Arctic soils currently store twice as much carbon as the entire atmosphere-two facts that make understanding how Arctic soil microbial communities are responding to climate change particularly urgent. Greening of vegetation cover across the Arctic landscape is one of the most prominent climate-driven shifts in Arctic terrestrial ecology, with potentially profound effects on biogeochemical cycling by the soil microbiome. Here we use metaproteomics to document microbial metabolic functions that drive soil carbon and nutrient cycling processes in an Arctic tundra landscape. We identify functional roles among bacterial taxonomic groups that are largely stable across vegetation types, with certain functions strongly expressed by rhizosphere groups reflecting a community metabolic response to greening.
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Affiliation(s)
- Samuel E Miller
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - Albert S Colman
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
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3
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Capovilla G, Braakman R, Fournier GP, Hackl T, Schwartzman J, Lu X, Yelton A, Longnecker K, Soule MCK, Thomas E, Swarr G, Mongera A, Payette JG, Castro KG, Waldbauer JR, Kujawinski EB, Cordero OX, Chisholm SW. Chitin utilization by marine picocyanobacteria and the evolution of a planktonic lifestyle. Proc Natl Acad Sci U S A 2023; 120:e2213271120. [PMID: 37159478 DOI: 10.1073/pnas.2213271120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
Marine picocyanobacteria Prochlorococcus and Synechococcus, the most abundant photosynthetic cells in the oceans, are generally thought to have a primarily single-celled and free-living lifestyle. However, while studying the ability of picocyanobacteria to supplement photosynthetic carbon fixation with the use of exogenous organic carbon, we found the widespread occurrence of genes for breaking down chitin, an abundant source of organic carbon that exists primarily as particles. We show that cells that encode a chitin degradation pathway display chitin degradation activity, attach to chitin particles, and show enhanced growth under low light conditions when exposed to chitosan, a partially deacetylated soluble form of chitin. Marine chitin is largely derived from arthropods, which underwent major diversifications 520 to 535 Mya, close to when marine picocyanobacteria are inferred to have appeared in the ocean. Phylogenetic analyses confirm that the chitin utilization trait was acquired at the root of marine picocyanobacteria. Together this leads us to postulate that attachment to chitin particles allowed benthic cyanobacteria to emulate their mat-based lifestyle in the water column, initiating their expansion into the open ocean, seeding the rise of modern marine ecosystems. Subsequently, transitioning to a constitutive planktonic life without chitin associations led to cellular and genomic streamlining along a major early branch within Prochlorococcus. Our work highlights how the emergence of associations between organisms from different trophic levels, and their coevolution, creates opportunities for colonizing new environments. In this view, the rise of ecological complexity and the expansion of the biosphere are deeply intertwined processes.
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Affiliation(s)
- Giovanna Capovilla
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Rogier Braakman
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Gregory P Fournier
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Thomas Hackl
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
- Groningen Institute of Evolutionary Life Sciences, University of Groningen, 9747 Groningen, Netherlands
| | - Julia Schwartzman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Xinda Lu
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Alexis Yelton
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Krista Longnecker
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 02543 Woods Hole, MA
| | - Melissa C Kido Soule
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 02543 Woods Hole, MA
| | - Elaina Thomas
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Gretchen Swarr
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 02543 Woods Hole, MA
| | - Alessandro Mongera
- Department of Pathology, Brigham and Women's Hospital, 02115 Boston, MA
- Department of Genetics, Harvard Medical School, 02115 Boston, MA
| | - Jack G Payette
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Kurt G Castro
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, 60637 Chicago, IL
| | - Elizabeth B Kujawinski
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 02543 Woods Hole, MA
| | - Otto X Cordero
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
| | - Sallie W Chisholm
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 02139 Cambridge, MA
- Department of Biology, Massachusetts Institute of Technology, 02139 Cambridge, MA
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4
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Ferreira D, Venceslau SS, Bernardino R, Preto A, Zhang L, Waldbauer JR, Leavitt WD, Pereira IAC. DsrC is involved in fermentative growth and interacts directly with the FlxABCD-HdrABC complex in Desulfovibrio vulgaris Hildenborough. Environ Microbiol 2023; 25:962-976. [PMID: 36602077 DOI: 10.1111/1462-2920.16335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 12/28/2022] [Indexed: 01/06/2023]
Abstract
DsrC is a key protein in dissimilatory sulfur metabolism, where it works as co-substrate of the dissimilatory sulfite reductase DsrAB. DsrC has two conserved cysteines in a C-terminal arm that are converted to a trisulfide upon reduction of sulfite. In sulfate-reducing bacteria, DsrC is essential and previous works suggested additional functions beyond sulfite reduction. Here, we studied whether DsrC also plays a role during fermentative growth of Desulfovibrio vulgaris Hildenborough, by studying two strains where the functionality of DsrC is impaired by a lower level of expression (IPFG07) and additionally by the absence of one conserved Cys (IPFG09). Growth studies coupled with metabolite and proteomic analyses reveal that fermentation leads to lower levels of DsrC, but impairment of its function results in reduced growth by fermentation and a shift towards more fermentative metabolism during sulfate respiration. In both respiratory and fermentative conditions, there is increased abundance of the FlxABCD-HdrABC complex and Adh alcohol dehydrogenase in IPFG09 versus the wild type, which is reflected in higher production of ethanol. Pull-down experiments confirmed a direct interaction between DsrC and the FlxABCD-HdrABC complex, through the HdrB subunit. Dissimilatory sulfur metabolism, where sulfur compounds are used for energy generation, is a key process in the ecology of anoxic environments, and is more widespread among bacteria than previously believed. Two central proteins for this type of metabolism are DsrAB dissimilatory sulfite reductase and its co-substrate DsrC. Using physiological, proteomic and biochemical studies of Desulfovibrio vulgaris Hildenborough and mutants affected in DsrC functionality, we show that DsrC is also relevant for fermentative growth of this model organism and that it interacts directly with the soluble FlxABCD-HdrABC complex that links the NAD(H) pool with dissimilatory sulfite reduction.
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Affiliation(s)
- Delfim Ferreira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Sofia S Venceslau
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Raquel Bernardino
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - André Preto
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Lichun Zhang
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
| | - William D Leavitt
- Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire, USA
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire, USA
| | - Inês A C Pereira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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5
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Zimmerman AE, Podowski JC, Gallagher GE, Coleman ML, Waldbauer JR. Tracking nitrogen allocation to proteome biosynthesis in a marine microbial community. Nat Microbiol 2023; 8:498-509. [PMID: 36635571 DOI: 10.1038/s41564-022-01303-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 12/12/2022] [Indexed: 01/14/2023]
Abstract
Microbial growth in many environments is limited by nitrogen availability, yet there is limited understanding of how complex communities compete for and allocate this resource. Here we develop a broadly applicable approach to track biosynthetic incorporation of 15N-labelled nitrogen substrates into microbial community proteomes, enabling quantification of protein turnover and N allocation to specific cellular functions in individual taxa. Application to oligotrophic ocean surface water identifies taxa-specific substrate preferences and a distinct subset of protein functions undergoing active biosynthesis. The cyanobacterium Prochlorococcus is the most effective competitor for acquisition of ammonium and urea and shifts its proteomic allocation of N over the day/night cycle. Our approach reveals that infrastructure and protein-turnover functions comprise substantial biosynthetic demand for N in Prochlorococcus and a range of other microbial taxa. The direct interrogation of the proteomic underpinnings of N limitation with 15N-tracking proteomics illuminates how nutrient stress differentially influences metabolism in co-existing microbes.
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Affiliation(s)
- Amy E Zimmerman
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA.,Biological Sciences Division, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Justin C Podowski
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA.,Division of Data Science and Learning, Argonne National Laboratory, Argonne, IL, USA
| | - Gwendolyn E Gallagher
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA.,New York Sea Grant, Stony Brook University, Stony Brook, NY, USA
| | - Maureen L Coleman
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA.
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6
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Luxem KE, Kraepiel AML, Zhang L, Waldbauer JR, Zhang X. Carbon substrate re-orders relative growth of a bacterium using Mo-, V-, or Fe-nitrogenase for nitrogen fixation. Environ Microbiol 2022; 24:2170-2176. [PMID: 35478483 DOI: 10.1111/1462-2920.16001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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7
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Luxem KE, Kraepiel AML, Zhang L, Waldbauer JR, Zhang X. Carbon substrate re-orders relative growth of a bacterium using Mo-, V-, or Fe-nitrogenase for nitrogen fixation. Environ Microbiol 2020; 22:1397-1408. [PMID: 32090445 PMCID: PMC7187303 DOI: 10.1111/1462-2920.14955] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/07/2020] [Indexed: 01/21/2023]
Abstract
Biological nitrogen fixation is catalyzed by the molybdenum (Mo), vanadium (V) and iron (Fe)‐only nitrogenase metalloenzymes. Studies with purified enzymes have found that the ‘alternative’ V‐ and Fe‐nitrogenases generally reduce N2 more slowly and produce more byproduct H2 than the Mo‐nitrogenase, leading to an assumption that their usage results in slower growth. Here we show that, in the metabolically versatile photoheterotroph Rhodopseudomonas palustris, the type of carbon substrate influences the relative rates of diazotrophic growth based on different nitrogenase isoforms. The V‐nitrogenase supports growth as fast as the Mo‐nitrogenase on acetate but not on the more oxidized substrate succinate. Our data suggest that this is due to insufficient electron flux to the V‐nitrogenase isoform on succinate compared with acetate. Despite slightly faster growth based on the V‐nitrogenase on acetate, the wild‐type strain uses exclusively the Mo‐nitrogenase on both carbon substrates. Notably, the differences in H2:N2 stoichiometry by alternative nitrogenases (~1.5 for V‐nitrogenase, ~4–7 for Fe‐nitrogenase) and Mo‐nitrogenase (~1) measured here are lower than prior in vitro estimates. These results indicate that the metabolic costs of V‐based nitrogen fixation could be less significant for growth than previously assumed, helping explain why alternative nitrogenase genes persist in diverse diazotroph lineages and are broadly distributed in the environment.
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Affiliation(s)
- Katja E Luxem
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
| | - Anne M L Kraepiel
- Princeton Environmental Institute, Princeton University, Princeton, NJ, 08544, USA
| | - Lichun Zhang
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | - Xinning Zhang
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA.,Princeton Environmental Institute, Princeton University, Princeton, NJ, 08544, USA
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8
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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: 150] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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.
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9
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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10
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Abstract
De novo sequencing offers an alternative to database search methods for peptide identification from mass spectra. Since it does not rely on a predetermined database of expected or potential sequences in the sample, de novo sequencing is particularly appropriate for samples lacking a well-defined or comprehensive reference database. However, the low accuracy of many de novo sequence predictions has prevented the widespread use of the variety of sequencing tools currently available. Here, we present a new open-source tool, Postnovo, that postprocesses de novo sequence predictions to find high-accuracy results. Postnovo uses a predictive model to rescore and rerank candidate sequences in a manner akin to database search postprocessing tools such as Percolator. Postnovo leverages the output from multiple de novo sequencing tools in its own analyses, producing many times the length of amino acid sequence information (including both full- and partial-length peptide sequences) at an equivalent false discovery rate (FDR) compared to any individual tool. We present a methodology to reliably screen the sequence predictions to a desired FDR given the Postnovo sequence score. We validate Postnovo with multiple data sets and demonstrate its ability to identify proteins that are missed by database search even in samples with paired reference databases.
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Affiliation(s)
- Samuel E Miller
- Department of the Geophysical Sciences , University of Chicago , 5734 South Ellis Avenue , Chicago , Illinois 60637 , United States
| | - Adriana I Rizzo
- Department of the Geophysical Sciences , University of Chicago , 5734 South Ellis Avenue , Chicago , Illinois 60637 , United States
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences , University of Chicago , 5734 South Ellis Avenue , Chicago , Illinois 60637 , United States
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11
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Ma X, Coleman ML, Waldbauer JR. Distinct molecular signatures in dissolved organic matter produced by viral lysis of marine cyanobacteria. Environ Microbiol 2018; 20:3001-3011. [PMID: 30047191 DOI: 10.1111/1462-2920.14338] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 06/21/2018] [Accepted: 06/21/2018] [Indexed: 11/29/2022]
Abstract
Dissolved organic matter (DOM) plays a central role in the microbial ecology and biogeochemistry of aquatic environments, yet little is known about how the mechanism of DOM release from its ultimate source, primary producer biomass, affects the molecular composition of the inputs to the dissolved pool. Here we used a model marine phytoplankton, the picocyanobacterium Synechococcus WH7803, to compare the composition of DOM released by three mechanisms: exudation, mechanical cell lysis and infection by the lytic phage S-SM1. A broad, untargeted analytical approach reveals the complexity of this freshly sourced DOM, and comparative analysis between DOM produced by the different mechanisms suggests that exudation and viral lysis are sources of unsaturated, oxygen-rich and possibly novel biomolecules. Furthermore, viral lysis of WH7803 by S-SM1 releases abundant peptides derived from specific proteolysis of the major light-harvesting protein phycoerythrin, raising the possibility that phage infection of these abundant cyanobacteria could be a significant source of high molecular weight dissolved organic nitrogen compounds.
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Affiliation(s)
- Xiufeng Ma
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | - Maureen L Coleman
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | - Jacob R Waldbauer
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
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12
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Schwartz MH, Waldbauer JR, Zhang L, Pan T. Global tRNA misacylation induced by anaerobiosis and antibiotic exposure broadly increases stress resistance in Escherichia coli. Nucleic Acids Res 2016; 44:10292-10303. [PMID: 27672035 PMCID: PMC5137444 DOI: 10.1093/nar/gkw856] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/14/2016] [Accepted: 09/16/2016] [Indexed: 12/22/2022] Open
Abstract
High translational fidelity is commonly considered a requirement for optimal cellular health and protein function. However, recent findings have shown that inducible mistranslation specifically with methionine engendered at the tRNA charging level occurs in mammalian cells, yeast and archaea, yet it was unknown whether bacteria were capable of mounting a similar response. Here, we demonstrate that Escherichia coli misacylates non-methionyl-tRNAs with methionine in response to anaerobiosis and antibiotic exposure via the methionyl–tRNA synthetase (MetRS). Two MetRS succinyl-lysine modifications independently confer high tRNA charging fidelity to the otherwise promiscuous, unmodified enzyme. Strains incapable of tRNA mismethionylation are less adept at growth in the presence of antibiotics and stressors. The presence of tRNA mismethionylation and its potential role in mistranslation within the bacterial domain establishes this response as a pervasive biological mechanism and connects it to diverse cellular functions and modes of fitness.
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Affiliation(s)
- Michael H Schwartz
- Department of Biochemistry and Molecular Biology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA.,Committee on Microbiology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA
| | - Jacob R Waldbauer
- Department of Geophysical Sciences, University of Chicago, 5734 S. Ellis Ave., Chicago, IL 60637, USA
| | - Lichun Zhang
- Department of Geophysical Sciences, University of Chicago, 5734 S. Ellis Ave., Chicago, IL 60637, USA
| | - Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA .,Committee on Microbiology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA
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Waldbauer JR, Rodrigue S, Coleman ML, Chisholm SW. Transcriptome and proteome dynamics of a light-dark synchronized bacterial cell cycle. PLoS One 2012; 7:e43432. [PMID: 22952681 PMCID: PMC3430701 DOI: 10.1371/journal.pone.0043432] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Accepted: 07/20/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Growth of the ocean's most abundant primary producer, the cyanobacterium Prochlorococcus, is tightly synchronized to the natural 24-hour light-dark cycle. We sought to quantify the relationship between transcriptome and proteome dynamics that underlie this obligate photoautotroph's highly choreographed response to the daily oscillation in energy supply. METHODOLOGY/PRINCIPAL FINDINGS Using RNA-sequencing transcriptomics and mass spectrometry-based quantitative proteomics, we measured timecourses of paired mRNA-protein abundances for 312 genes every 2 hours over a light-dark cycle. These temporal expression patterns reveal strong oscillations in transcript abundance that are broadly damped at the protein level, with mRNA levels varying on average 2.3 times more than the corresponding protein. The single strongest observed protein-level oscillation is in a ribonucleotide reductase, which may reflect a defense strategy against phage infection. The peak in abundance of most proteins also lags that of their transcript by 2-8 hours, and the two are completely antiphase for some genes. While abundant antisense RNA was detected, it apparently does not account for the observed divergences between expression levels. The redirection of flux through central carbon metabolism from daytime carbon fixation to nighttime respiration is associated with quite small changes in relative enzyme abundances. CONCLUSIONS/SIGNIFICANCE Our results indicate that expression responses to periodic stimuli that are common in natural ecosystems (such as the diel cycle) can diverge significantly between the mRNA and protein levels. Protein expression patterns that are distinct from those of cognate mRNA have implications for the interpretation of transcriptome and metatranscriptome data in terms of cellular metabolism and its biogeochemical impact.
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Affiliation(s)
- Jacob R. Waldbauer
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Joint Program in Chemical Oceanography, Woods Hole Oceanographic Institution and Massachusetts Institute of Technology, Cambridge Massachusetts, United States of America
| | - Sébastien Rodrigue
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Maureen L. Coleman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge Massachusetts, United States of America
| | - Sallie W. Chisholm
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Department of Biology, Massachusetts Institute of Technology, Cambridge Massachusetts, United States of America
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Abstract
There is a close connection between modern-day biosynthesis of particular triterpenoid biomarkers and presence of molecular oxygen in the environment. Thus, the detection of steroid and triterpenoid hydrocarbons far back in Earth history has been used to infer the antiquity of oxygenic photosynthesis. This prompts the question: were these compounds produced similarly in the past? In this paper, we address this question with a review of the current state of knowledge surrounding the oxygen requirement for steroid biosynthesis and phylogenetic patterns in the distribution of steroid and triterpenoid biosynthetic pathways. The hopanoid and steroid biosynthetic pathways are very highly conserved within the bacterial and eukaryotic domains, respectively. Bacteriohopanepolyols are produced by a wide range of bacteria, and are methylated in significant abundance at the C2 position by oxygen-producing cyanobacteria. On the other hand, sterol biosynthesis is sparsely distributed in distantly related bacterial taxa and the pathways do not produce the wide range of products that characterize eukaryotes. In particular, evidence for sterol biosynthesis by cyanobacteria appears flawed. Our experiments show that cyanobacterial cultures are easily contaminated by sterol-producing rust fungi, which can be eliminated by treatment with cycloheximide affording sterol-free samples. Sterols are ubiquitous features of eukaryotic membranes, and it appears likely that the initial steps in sterol biosynthesis were present in their modern form in the last common ancestor of eukaryotes. Eleven molecules of O2 are required by four enzymes to produce one molecule of cholesterol. Thermodynamic arguments, optimization of function and parsimony all indicate that an ancestral anaerobic pathway is highly unlikely. The known geological record of molecular fossils, especially steranes and triterpanes, is notable for the limited number of structural motifs that have been observed. With a few exceptions, the carbon skeletons are the same as those found in the lipids of extant organisms and no demonstrably extinct structures have been reported. Furthermore, their patterns of occurrence over billion year time-scales correlate strongly with environments of deposition. Accordingly, biomarkers are excellent indicators of environmental conditions even though the taxonomic affinities of all biomarkers cannot be precisely specified. Biomarkers are ultimately tied to biochemicals with very specific functional properties, and interpretations of the biomarker record will benefit from increased understanding of the biological roles of geologically durable molecules.
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Affiliation(s)
- Roger E Summons
- Massachusetts Institute of Technology, Department of Earth, Atmospheric and Planetary Sciences, 77 Massachusetts Avenue E34-246, Cambridge, MA 02139-4307, USA.
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Abstract
Earth's biogeochemical cycle of carbon delivers both limestones and organic materials to the crust. In numerous, biologically catalysed redox reactions, hydrogen, sulphur, iron, and oxygen serve prominently as electron donors and acceptors. The progress of these reactions can be reconstructed from records of variations in the abundance of 13C in sedimentary carbonate minerals and organic materials. Because the crust is always receiving new CO2 from the mantle and a portion of it is being reduced by photoautotrophs, the carbon cycle has continuously released oxidizing power. Most of it is represented by Fe3+ that has accumulated in the crust or been returned to the mantle via subduction. Less than 3% of the estimated, integrated production of oxidizing power since 3.8 Gyr ago is represented by O2 in the atmosphere and dissolved in seawater. The balance is represented by sulphate. The accumulation of oxidizing power can be estimated from budgets summarizing inputs of mantle carbon and rates of organic-carbon burial, but levels of O2 are only weakly and indirectly coupled to those phenomena and thus to carbon-isotopic records. Elevated abundances of 13C in carbonate minerals ca 2.3 Gyr old, in particular, are here interpreted as indicating the importance of methanogenic bacteria in sediments rather than increased burial of organic carbon.
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Affiliation(s)
- John M Hayes
- Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Woods Hole, MA 02543, USA.
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Chamberlain CP, Waldbauer JR, Fox-Dobbs K, Newsome SD, Koch PL, Smith DR, Church ME, Chamberlain SD, Sorenson KJ, Risebrough R. Pleistocene to recent dietary shifts in California condors. Proc Natl Acad Sci U S A 2005; 102:16707-11. [PMID: 16275902 PMCID: PMC1283853 DOI: 10.1073/pnas.0508529102] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We used carbon and nitrogen isotopes to investigate changes in the diet of California condors from the Pleistocene to the recent. During the Pleistocene, condors from California fed on both terrestrial megafauna and marine mammals. Early accounts reported condors feeding on the carcasses of marine mammals, but by the late 1700s, condor diets had shifted predominantly to terrestrial animals, following the commercial harvesting of marine mammals and the development of cattle ranching on land. At present, dairy calves provided by humans significantly augment condor diet, constituting an artificial support of the current population. Reestablishing a marine mammal component in the condor diet may be an effective strategy for fostering viable condor populations independent of direct human subsidies.
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Affiliation(s)
- C P Chamberlain
- Department of Geological and Environmental Science, Stanford University, Stanford, CA 94305-2115, USA.
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Rubenstein DR, Chamberlain CP, Holmes RT, Ayres MP, Waldbauer JR, Graves GR, Tuross NC. Linking breeding and wintering ranges of a migratory songbird using stable isotopes. Science 2002; 295:1062-5. [PMID: 11834833 DOI: 10.1126/science.1067124] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We used the natural abundance of stable isotopes (carbon and hydrogen) in the feathers of a neotropical migrant songbird to determine where birds from particular breeding areas spend the winter and the extent to which breeding populations mix in winter quarters. We show that most birds wintering on western Caribbean islands come from the northern portion of the species' North American breeding range, whereas those on more easterly islands are primarily from southern breeding areas. Although segregated by breeding latitude, birds within local wintering areas derive from a wide range of breeding longitudes, indicating considerable population mixing with respect to breeding longitude. These results are useful for assessing the effects of wintering habitat loss on breeding population abundances and for predicting whether the demographic consequences will be concentrated or diffuse.
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Affiliation(s)
- D R Rubenstein
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
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