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US 2013/0157331 A1Published application
Pnp gene modification for improved xylose utilization in zymomonas
AssigneeE. I. Du Pont de Nemours and Company
InventorsPERRY G. CAIMI, Min Qi, Luan Tao, Paul V. Viitanen, Jianjun Yang
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Abstract
The endogenous pnp gene encoding polynucleotide phosphorylase in the Zymomonas genome was identified as a target for modification to provide improved xylose utilizing cells for ethanol production. The cells are in addition genetically modified to have increased expression of ribose-5-phosphate isomerase (RPI) activity, as compared to cells without this genetic modification, and are not limited in xylose isomerase activity in the absence of the pnp modification.
Claims16
A recombinant bacterial host cell comprising:
- a) a xylose metabolic pathway comprising at least one polypeptide having xylose isomerase activity;
- b) at least one genetic modification which increases ribose-5-phosphate isomerase activity in the host cell as compared with ribose-5-phosphate isomerase activity in the host cell lacking said genetic modification;
- and
- c) at least one genetic modification in the sequence of an endogenous gene encoding polynucleotide phosphorylase that shortens the coding region resulting in expression of a C-terminal truncated protein;
- wherein the bacterial host cell utilizes xylose to produce ethanol, and the xylose isomerase activity is not limiting in the bacterial host cell.
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Dependencies are inferred from the claim text.