The use of an acetoacetyl-CoA synthase in place of a -ketothiolase enhances poly-3-hydroxybutyrate production in sugarcane mesophyll cells

McQualter, Richard B., Petrasovits, Lars A., Gebbie, Leigh K., Schweitzer, Dirk, Blackman, Deborah M., Chrysanthopoulos, Panagiotis, Hodson, Mark P., Plan, Manuel R., Riches, James D., Snell, Kristi D., Brumbley, Stevens M., & Nielsen, Lars K. (2015) The use of an acetoacetyl-CoA synthase in place of a -ketothiolase enhances poly-3-hydroxybutyrate production in sugarcane mesophyll cells. Plant Biotechnology Journal, 13(5), pp. 700-707.

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Engineering the production of polyhydroxyalkanoates (PHAs) into high biomass bioenergy crops has the potential to provide a sustainable supply of bioplastics and energy from a single plant feedstock. One of the major challenges in engineering C-4 plants for the production of poly[(R)-3-hydroxybutyrate] (PHB) is the significantly lower level of polymer produced in the chloroplasts of mesophyll (M) cells compared to bundle sheath (BS) cells, thereby limiting the full PHB yield-potential of the plant. In this study, we provide evidence that the access to substrate for PHB synthesis may limit polymer production in M chloroplasts. Production of PHB in M cells of sugarcane is significantly increased by replacing -ketothiolase, the first enzyme in the bacterial PHA pathway, with acetoacetyl-CoA synthase. This novel pathway enabled the production of PHB reaching an average of 6.3% of the dry weight of total leaf biomass, with levels ranging from 3.6 to 11.8% of the dry weight (DW) of individual leaves. These yields are more than twice the level reported in PHB-producing sugarcane containing the -ketothiolase and illustrate the importance of producing polymer in mesophyll plastids to maximize yield. The molecular weight of the polymer produced was greater than 2x10(6)Da. These results are a major step forward in engineering a high biomass C-4 grass for the commercial production of PHB.

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ID Code: 91539
Item Type: Journal Article
Refereed: Yes
Additional Information: The authors thank the Central Glasshouse Services Unit at the University of Queensland for maintaining the sugarcane plants in good condition. We also thank Panagiotis Chrysanthopoulos 3, and Manuel Plan of Metabolomics Australia Queensland Node and Sean Daughtry, Mirel Sharxhi and Muna Ray of Metabolix for analytical assistance. This study was funded through ARC linkage grant LP100100659 and Metabolix, Inc. D.S. and K.D.S. are employees of Metabolix, Inc.
Funders: ARC, Metabolix, Inc.
Keywords: polyhydroxybutyrate, PHB, sugarcane, b-ketothiolase, acetoacetyl- CoA synthase, NphT7, biopolymer
DOI: 10.1111/pbi.12298
ISSN: 1467-7644
Divisions: Current > Schools > School of Earth, Environmental & Biological Sciences
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Deposited On: 18 Apr 2016 01:18
Last Modified: 18 Apr 2016 21:49

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