Synergistic effects of 2A-mediated polyproteins on the production of lignocellulose degradation enzymes in tobacco plants

J Exp Bot. 2012 Aug;63(13):4797-810. doi: 10.1093/jxb/ers159. Epub 2012 Jul 12.

Abstract

Cost-effective bioethanol production requires a supply of various low-cost enzymes that can hydrolyse lignocellulosic materials consisting of multiple polymers. Because plant-based enzyme expression systems offer low-cost and large-scale production, this study simultaneously expressed β-glucosidase (BglB), xylanase (XylII), exoglucanase (E3), and endoglucanase (Cel5A) in tobacco plants, which were individually fused with chloroplast-targeting transit peptides and linked via the 2A self-cleaving oligopeptideex from foot-and-mouth disease virus (FMDV) as follows: [RsBglB-2A-RaCel5A], [RsXylII-2A-RaCel5A], and [RsE3-2A-RaCel5A]. The enzymes were targeted to chloroplasts in tobacco cells and their activities were confirmed. Similarly to the results of a transient assay using Arabidopsis thaliana protoplasts, when XylII was placed upstream of the 2A sequence, the [RsXylII-2A-RaCel5A] transgenic tobacco plant had a more positive influence on expression of the protein placed downstream. The [RsBglB-2A-RaCel5A] and [RsE3-2A-RaCel5A] transgenic lines displayed higher activities towards carboxylmethylcellulose (CMC) compared to those in the [RsXylII-2A-RaCel5A] transgenic line. This higher activity was attributable to the synergistic effects of the different cellulases used. The [RsBglB-2A-RaCel5A] lines exhibited greater efficiency (35-74% increase) of CMC hydrolysis when the exoglucanase CBHII was added. Among the various exoglucanases, E3 showed higher activity with the crude extract of the [RsBglB-2A-RaCel5A] transgenic line. Transgenic expression of 2A-mediated multiple enzymes induced synergistic effects and led to more efficient hydrolysis of lignocellulosic materials for bioethanol production.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Arabidopsis / ultrastructure
  • Cellulase / genetics
  • Cellulase / metabolism
  • Cellulases / genetics
  • Cellulases / metabolism
  • Chloroplasts / enzymology*
  • Endo-1,4-beta Xylanases / genetics
  • Endo-1,4-beta Xylanases / metabolism
  • Foot-and-Mouth Disease Virus / genetics
  • Hydrolysis
  • Kinetics
  • Lignin / metabolism*
  • Nicotiana / enzymology*
  • Nicotiana / genetics
  • Nicotiana / ultrastructure
  • Plant Leaves / enzymology
  • Plant Leaves / genetics
  • Plant Leaves / ultrastructure
  • Plants, Genetically Modified
  • Polyproteins / genetics
  • Polyproteins / metabolism*
  • Protein Sorting Signals
  • Protein Transport
  • Trichoderma / enzymology
  • Trichoderma / genetics

Substances

  • Polyproteins
  • Protein Sorting Signals
  • lignocellulose
  • Lignin
  • Cellulases
  • Cellulase
  • Endo-1,4-beta Xylanases