Metabolic engineering strategies have been successfully implemented to improve the production of isobutanol,a next-generation biofuel,in Saccharomyces ***,we explore how two of these strategies,pathway re-localization...
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Metabolic engineering strategies have been successfully implemented to improve the production of isobutanol,a next-generation biofuel,in Saccharomyces ***,we explore how two of these strategies,pathway re-localization and redox cofactor-balancing,affect the performance and physiology of isobutanol producing *** equipped yeast with isobutanol cassettes which had either a mitochondrial or cytosolic localized isobutanol pathway and used either a redox-imbalanced(NADPH-dependent)or redox-balanced(NADH-dependent)ketol-acid reductoisomerase *** then conducted transcriptomic,proteomic and metabolomic analyses to elucidate molecular differences between the engineered *** localization had a large effect on isobutanol production with the strain expressing the mitochondrial-localized enzymes producing 3.8-fold more isobutanol than strains expressing the cytosolic ***-balancing did not improve isobutanol titers and instead the strain with the redox-imbalanced pathway produced 1.5-fold more isobutanol than the balanced version,albeit at low overall pathway *** genomic analyses suggested that the poor performances of the cytosolic pathway strains were in part due to a shortage in cytosolic Fe-S clusters,which are required cofactors for the dihydroxyacid dehydratase *** then demonstrated that this cofactor limitation may be partially recovered by disrupting iron homeostasis with a fra2 mutation,thereby increasing cellular iron *** resulting isobutanol titer of the fra2 null strain harboring a cytosolic-localized isobutanol pathway outperformed the strain with the mitochondrial-localized pathway by 1.3-fold,demonstrating that both localizations can support flux to isobutanol.
Background Large-river decision-makers are charged with maintaining diverse ecosystem services through unprec-edented social-ecological transformations as climate change and other global stressors *** interconnected,d...
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Background Large-river decision-makers are charged with maintaining diverse ecosystem services through unprec-edented social-ecological transformations as climate change and other global stressors *** interconnected,dendritic habitats of rivers,which often demarcate jurisdictional boundaries,generate complex management ***,we explore how the Resist–Accept–Direct(RAD)framework may enhance large-river management by promoting coordinated and deliberate responses to social-ecological trajectories of *** RAD frame-work identifies the full decision space of potential management approaches,wherein managers may resist change to maintain historical conditions,accept change toward different conditions,or direct change to a specified future with novel *** the Upper Mississippi River System,managers are facing social-ecological transformations from more frequent and extreme high-water *** illustrate how RAD-informed basin-,reach-,and site-scale decisions could:(1)provide cross-spatial scale framing;(2)open the entire decision space of potential management approaches;and(3)enhance coordinated inter-jurisdictional management in response to the trajectory of the Upper Mississippi River *** The RAD framework helps identify plausible long-term trajectories in different reaches(or subbasins)of the river and how the associated social-ecological transformations could be managed by altering site-scale *** reach-scale objectives may reprioritize how,where,and when site conditions could be altered to contribute to the basin goal,given the basin’s plausible trajectories of change(e.g.,by coordinating action across sites to alter habitat connectivity,diversity,and redundancy in the river mosaic).Conclusions When faced with long-term systemic transformations(e.g.,>50 years),the RAD framework helps explicitly consider whether or when the basin vision or goals may no longer be achievable,and direct options may open y
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