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Bacterial microcompartment-directed polyphosphate kinase promotes stable polyphosphate accumulation in E. coli

Liang, M; Frank, S; Lünsdorf, H; Warren, MJ; Prentice, MB; (2017) Bacterial microcompartment-directed polyphosphate kinase promotes stable polyphosphate accumulation in E. coli. Biotechnology Journal , 12 (3) , Article 1600415. 10.1002/biot.201600415. Green open access

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Abstract

Processes for the biological removal of phosphate from wastewater rely on temporary manipula-tion 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 hypothesized that partitioning PPK1 from cytoplasmic exopoly phosphatases would increase and stabilize 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 polyphos-phate 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 eight-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 compartmentali-zation of a polymerizing 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.

Type: Article
Title: Bacterial microcompartment-directed polyphosphate kinase promotes stable polyphosphate accumulation in E. coli
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/biot.201600415
Publisher version: http://doi.org/10.1002/biot.201600415
Language: English
Keywords: Bacteria, Biopolymers, Metabolic engineering, Microreactors, Synthetic biology
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Biochemical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1547394
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