Plant Science

Biofuel Self-Engineering

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Science  02 Nov 2012:
Vol. 338, Issue 6107, pp. 582
DOI: 10.1126/science.338.6107.582-b
CREDIT: ADAPTED FROM B. SHEN ET AL., NAT. BIOTECHNOL. 30 (21 OCTOBER 2012) © 2012 NATURE PUBLISHING GROUP

Biofuels could be a useful substitute for fossil fuels, but various aspects of the production process need improvement to increase yield and reduce costs. One approach would be to express processing enzymes in the growing plant itself. However, to avoid damage to the growing plant, the enzymes need to be held at bay until the time comes to convert cell walls into soluble sugars. Shen et al. have tackled this challenge in maize, for which xylanase can be used to break down cell walls into fermentable carbohydrates. Expression of xylanase in the plant alleviates problems of enzyme production and access to substrates, but at the same time produces problems in damaging plant growth, for example, yielding shriveled seeds. The xylanase was brought under control by adding an intein, a self-splicing peptide from the bacterium Thermus thermophilus. Use of a thermostable xylanase meant that treatment of the plant material containing the hybrid protein with temperatures in the range of 60° to 70°C resulted in removal of the inhibitory peptide and the generation of functional xylanase. With an optimized version of the hybrid xylanase-intein, transgenic plants showed normal development and normal seed set, and improved biomass conversion to glucose and xylose.

Nat. Biotechnol. 30, 10.1038/nbt.2402 (2012).

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