Affiliation:
1. Department of Biomaterials Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
Abstract
ABSTRACT
The wood decay basidiomycete
Phanerochaete chrysosporium
produces a variety of cellobiohydrolases belonging to glycoside hydrolase (GH) families 6 and 7 in the presence of cellulose. However, no inducer of the production of these enzymes has yet been identified. Here, we quantitatively compared the transcript levels of the genes encoding GH family 6 cellobiohydrolase (
cel6A
) and GH family 7 cellobiohydrolase isozymes (
cel7A
to
cel7F/G
) in cultures containing glucose, cellulose, and cellooligosaccharides by real-time quantitative PCR, in order to evaluate the transcription-inducing effect of soluble sugars. Upregulation of transcript levels in the presence of cellulose compared to glucose was observed for
cel7B
,
cel7C
,
cel7D
,
cel7F/G
, and
cel6A
at all time points during cultivation. In particular, the transcription of
cel7C
and
cel7D
was strongly induced by cellotriose or cellotetraose. The highest level of
cel7C
transcripts was observed in the presence of cellotetraose, whereas the highest level of
cel7D
transcripts was found in the presence of cellotriose, amounting to 2.7 × 10
6
and 1.7 × 10
6
copies per 10
5
actin gene transcripts, respectively. These numbers of
cel7C
and
cel7D
transcripts were higher than those in the presence of cellulose. In contrast, cellobiose had a weaker transcription-inducing effect than either cellotriose or cellotetraose for
cel7C
and had little effect in the case of
cel7D
. These results indicate that cellotriose and cellotetraose, but not cellobiose, are possible natural cellobiohydrolase gene transcription inducers derived from cellulose.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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