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Bacterial microcompartment-directed polyphosphate kinase promotes stable polyphosphate accumulation in E. coli
Warren, Martin J.
Prentice, Michael B.
Processes for the biological removal of phosphate from wastewater rely on temporary manipulation of bacterial polyphosphate levels by phased environmental stimuli. In E. coli polyphosphate levels are controlled via the polyphosphate-synthesizing enzyme polyphosphate kinase (PPK1) and exopolyphosphatases (PPX and GPPA), and are temporarily enhanced by PPK1 overexpression and reduced by PPX overexpression. We hypothesised that partitioning PPK1 from cytoplasmic exopolyphosphatases would increase and stabilise E. coli polyphosphate levels. Partitioning was achieved by co-expression of E. coli PPK1 fused with a microcompartment-targeting sequence and an artificial operon of Citrobacter freundii bacterial microcompartment genes. Encapsulation of targeted PPK1 resulted in persistent phosphate uptake and stably increased cellular polyphosphate levels throughout cell growth and into the stationary phase, while PPK1 overexpression alone produced temporary polyphosphate increase and phosphate uptake. Targeted PPK1 increased polyphosphate in microcompartments 8-fold compared with non-targeted PPK1. Co-expression of PPX polyphosphatase with targeted PPK1 had little effect on elevated cellular polyphosphate levels because microcompartments retained polyphosphate. Co-expression of PPX with non-targeted PPK1 reduced cellular polyphosphate levels. Thus, subcellular compartmentalisation of a polymerising enzyme sequesters metabolic products from competing catabolism by preventing catabolic enzyme access. Specific application of this process to polyphosphate is of potential application for biological phosphate removal.
Bacteria , Biopolymers , Metabolic engineering , Microreactors , Synthetic biology , Escherichia coli , Inorganic polyphosphate , Waste water , Salmonella enterica , Protein , Phosphate , Gene , Metabolism , Organelles , Sequences
Liang, M., Frank, S., Lünsdorf, H., Warren, M. J. and Prentice, M. B. (2017) 'Bacterial microcompartment-directed polyphosphate kinase promotes stable polyphosphate accumulation in E. coli', Biotechnology Journal, 12(3), 1600415
This is the accepted version of the following article: Liang et al (2017), Bacterial microcompartment-directed polyphosphate kinase promotes stable polyphosphate accumulation in E. coli. Biotechnol. J., 12: 1600415 which has been published in final form at http://dx.doi.org/10.1002/biot.201600415 .This article may be used for non-commercial purposes in accordance with the Wiley Self-Archiving Policy [olabout.wiley.com/WileyCDA/Section/id-820227.html]