Deconstructing the Dissimilatory Sulfate Reduction Pathway:Isotope Fractionation of a Mutant Unable of Growth on Sulfate
Autor: | Emma Bertran, William D. Leavitt, Andre Pellerin, Grant M. Zane, Judy D. Wall, Itay Halevy, Boswell A. Wing, David T. Johnston |
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Jazyk: | angličtina |
Rok vydání: | 2018 |
Předmět: |
0301 basic medicine
Microbiology (medical) 030106 microbiology lcsh:QR1-502 chemistry.chemical_element PROTEIN BACTERIAL REDUCTION Redox Microbiology lcsh:Microbiology 03 medical and health sciences chemistry.chemical_compound Isotope fractionation Sulfite Dissimilatory sulfate reduction Sulfate deletion mutant Desulfovibrio vulgaris SULFUR ISOTOPES Original Research chemostat BISULFITE ION biology sulfite reduction metabolic pathway biology.organism_classification Sulfur EVOLUTION MODEL Metabolic pathway 030104 developmental biology chemistry Biochemistry 13. Climate action BIOTURBATION sulfur isotope fractionation MARINE |
Zdroj: | Bertran, E, Leavitt, W D, Pellerin, A, Zane, G M, Wall, J D, Halevy, I, Wing, B A & Johnston, D T 2018, ' Deconstructing the Dissimilatory Sulfate Reduction Pathway : Isotope Fractionation of a Mutant Unable of Growth on Sulfate ', Frontiers in Microbiology, vol. 9, 3110 . https://doi.org/10.3389/fmicb.2018.03110 Frontiers in Microbiology, Vol 9 (2018) Frontiers in Microbiology |
Popis: | The sulfur isotope record provides key insight into the history of Earth's redox conditions. A detailed understanding of the metabolisms driving this cycle, and specifically microbial sulfate reduction (MSR), is crucial for accurate paleoenvironmental reconstructions. This includes a precise knowledge of the step-specific sulfur isotope effects during MSR. In this study, we aim at resolving the cellular-level fractionation factor during dissimilatory sulfite reduction to sulfide within MSR, and use this measured isotope effect as a calibration to enhance our understanding of the biochemistry of sulfite reduction. For this, we merge measured isotope effects associated with dissimilatory sulfite reduction with a quantitative model that explicitly links net fractionation, reaction reversibility, and intracellular metabolite levels. The highly targeted experimental aspect of this study was possible by virtue of the availability of a deletion mutant strain of the model sulfate reducer Desulfovibrio vulgaris (strain Hildenborough), in which the sulfite reduction step is isolated from the rest of the metabolic pathway owing to the absence of its QmoABC complex (Delta Qmo). This deletion disrupts electron flux and prevents the reduction of adenosine phosphosulfate (APS) to sulfite. When grown in open-system steady-state conditions at 10% maximum growth rate in the presence of sulfite and lactate as electron donor, sulfur isotope fractionation factors averaged -15.9 parts per thousand (1 sigma = 0.4), which appeared to be statistically indistinguishable from a pure enzyme study with dissimilatory sulfite reductase. We coupled these measurements with an understanding of step-specific equilibrium and kinetic isotope effects, and furthered our mechanistic understanding of the biochemistry of sulfite uptake and ensuing reduction. Our metabolically informed isotope model identifies flavodoxin as the most likely electron carrier performing the transfer of electrons to dissimilatory sulfite reductase. This is in line with previous work on metabolic strategies adopted by sulfate reducers under different energy regimes, and has implications for our understanding of the plasticity of this metabolic pathway at the center of our interpretation of modern and palaeo-environmental records. |
Databáze: | OpenAIRE |
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