TY - JOUR
T1 - Autohydrolysis of plant xylans by apoplastic expression of thermophilic bacterial endo-xylanases
AU - Borkhardt, Bernhard
AU - Harholt, Jesper
AU - Ulvskov, Peter Bjarne
AU - Ahring, Birgitte Kiær
AU - Jørgensen, Bodil
AU - Brinch-Pedersen, Henrik
PY - 2010/4
Y1 - 2010/4
N2 - The genes encoding the two endo-xylanases XynA and XynB from the thermophilic bacterium Dictyoglomus thermophilum were codon optimized for expression in plants. Both xylanases were designed to be constitutively expressed under the control of the CaMV 35S promoter and targeted to the apoplast. Transient expression in tobacco and stable expression in transgenic Arabidopsis showed that both enzymes were expressed in an active form with temperature optima at 85 °C. Transgenic Arabidopsis accumulating heterologous endo-xylanases appeared phenotypically normal and were fully fertile. The highest xylanase activity in Arabidopsis was found in dry stems indicating that the enzymes were not degraded during stem senescence. High levels of enzyme activity were maintained in cell-free extracts from dry transgenic stems during incubation at 85 °C for 24 h. Analysis of cell wall polysaccharides after heat treatment of wildtype and transgenic extracts from dry stems showed a decrease in the molecular weight of xylans from transgenic stems.
AB - The genes encoding the two endo-xylanases XynA and XynB from the thermophilic bacterium Dictyoglomus thermophilum were codon optimized for expression in plants. Both xylanases were designed to be constitutively expressed under the control of the CaMV 35S promoter and targeted to the apoplast. Transient expression in tobacco and stable expression in transgenic Arabidopsis showed that both enzymes were expressed in an active form with temperature optima at 85 °C. Transgenic Arabidopsis accumulating heterologous endo-xylanases appeared phenotypically normal and were fully fertile. The highest xylanase activity in Arabidopsis was found in dry stems indicating that the enzymes were not degraded during stem senescence. High levels of enzyme activity were maintained in cell-free extracts from dry transgenic stems during incubation at 85 °C for 24 h. Analysis of cell wall polysaccharides after heat treatment of wildtype and transgenic extracts from dry stems showed a decrease in the molecular weight of xylans from transgenic stems.
U2 - 10.1111/j.1467-7652.2010.00506.x
DO - 10.1111/j.1467-7652.2010.00506.x
M3 - Journal article
C2 - 20384855
SN - 1467-7644
VL - 8
SP - 363
EP - 374
JO - Plant Biotechnology Journal
JF - Plant Biotechnology Journal
IS - 3
ER -