TY - JOUR
T1 - The impact of a single-nucleotide mutation of bgl2 on cellulase induction in a Trichoderma reesei mutant
AU - Shida, Yosuke
AU - Yamaguchi, Kaori
AU - Nitta, Mikiko
AU - Nakamura, Ayana
AU - Takahashi, Machiko
AU - Kidokoro, Shun Ichi
AU - Mori, Kazuki
AU - Tashiro, Kosuke
AU - Kuhara, Satoru
AU - Matsuzawa, Tomohiko
AU - Yaoi, Katsuro
AU - Sakamoto, Yasumitsu
AU - Tanaka, Nobutada
AU - Morikawa, Yasushi
AU - Ogasawara, Wataru
N1 - Funding Information:
The authors thank Dr. Satoshi Nakagawa from Kyowa Hakko Bio Co., Ltd. and Dr. Hirakawa Hideki from Kazusa DNA Res. Inst. for their valuable comments on comparative genome analysis, as well as Dr. Hiroaki Motoyama and Yoshi‑ yuki Yonetani from Kyowa Hakko Bio Co., Ltd. for their generosity in providing the T. reesei mutants. A part of this research was supported by Grants‑in‑Aid for Scientific Research from Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (No. 23603002) and by a SATREPS Grant from Japan Science and Technology Agency (JST) and Japan International Cooperation Agency (JICA).
Publisher Copyright:
© 2015 Shida et al.
PY - 2015/12/30
Y1 - 2015/12/30
N2 - Background: The filamentous fungus Trichoderma reesei (anamorph of Hypocrea jecorina) produces increased cellulase expression when grown on cellulose or its derivatives as a sole carbon source. It has been believed that β-glucosidases of T. reesei not only metabolize cellobiose but also contribute in the production of inducers of cellulase gene expression by their transglycosylation activity. The cellulase hyper-producing mutant PC-3-7 developed in Japan has enhanced cellulase production ability when cellobiose is used as the inducer. The comparative genomics analysis of PC-3-7 and its parent revealed a single-nucleotide mutation within the bgl2 gene encoding intracellular β-glucosidase II (BGLII/Cel1a), giving rise to an amino acid substitution in PC-3-7, which could potentially account for the enhanced cellulase expression when these strains are cultivated on cellulose and cellobiose. Results: To analyze the effects of the BGLII mutation in cellulase induction, we constructed both a bgl2 revertant and a disruptant. Enzymatic analysis of the transformant lysates showed that the strain expressing mutant BGLII exhibited weakened cellobiose hydrolytic activity, but produced some transglycosylation products, suggesting that the SNP in bgl2 strongly diminished cellobiase activity, but did not result in complete loss of function of BGLII. The analysis of the recombinant BGLII revealed that transglycosylation products might be oligosaccharides, composed probably of glucose linked β-1,4, β-1,3, or a mixture of both. PC-3-7 revertants of bgl2 exhibited reduced expression and inducibility of cellulase during growth on cellulose and cellobiose substrates. Furthermore, the effect of this bgl2 mutation was reproduced in the common strain QM9414 in which the transformants showed cellulase production comparable to that of PC-3-7. Conclusion: We conclude that BGLII plays an important role in cellulase induction in T. reesei and that the bgl2 mutation in PC-3-7 brought about enhanced cellulase expression on cellobiose. The results of the investigation using PC-3-7 suggested that other mutation(s) in PC-3-7 could also contribute to cellulase induction. Further investigation is essential to unravel the mechanism responsible for cellulase induction in T. reesei.
AB - Background: The filamentous fungus Trichoderma reesei (anamorph of Hypocrea jecorina) produces increased cellulase expression when grown on cellulose or its derivatives as a sole carbon source. It has been believed that β-glucosidases of T. reesei not only metabolize cellobiose but also contribute in the production of inducers of cellulase gene expression by their transglycosylation activity. The cellulase hyper-producing mutant PC-3-7 developed in Japan has enhanced cellulase production ability when cellobiose is used as the inducer. The comparative genomics analysis of PC-3-7 and its parent revealed a single-nucleotide mutation within the bgl2 gene encoding intracellular β-glucosidase II (BGLII/Cel1a), giving rise to an amino acid substitution in PC-3-7, which could potentially account for the enhanced cellulase expression when these strains are cultivated on cellulose and cellobiose. Results: To analyze the effects of the BGLII mutation in cellulase induction, we constructed both a bgl2 revertant and a disruptant. Enzymatic analysis of the transformant lysates showed that the strain expressing mutant BGLII exhibited weakened cellobiose hydrolytic activity, but produced some transglycosylation products, suggesting that the SNP in bgl2 strongly diminished cellobiase activity, but did not result in complete loss of function of BGLII. The analysis of the recombinant BGLII revealed that transglycosylation products might be oligosaccharides, composed probably of glucose linked β-1,4, β-1,3, or a mixture of both. PC-3-7 revertants of bgl2 exhibited reduced expression and inducibility of cellulase during growth on cellulose and cellobiose substrates. Furthermore, the effect of this bgl2 mutation was reproduced in the common strain QM9414 in which the transformants showed cellulase production comparable to that of PC-3-7. Conclusion: We conclude that BGLII plays an important role in cellulase induction in T. reesei and that the bgl2 mutation in PC-3-7 brought about enhanced cellulase expression on cellobiose. The results of the investigation using PC-3-7 suggested that other mutation(s) in PC-3-7 could also contribute to cellulase induction. Further investigation is essential to unravel the mechanism responsible for cellulase induction in T. reesei.
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U2 - 10.1186/s13068-015-0420-y
DO - 10.1186/s13068-015-0420-y
M3 - Article
AN - SCOPUS:84952320174
SN - 1754-6834
VL - 8
JO - Biotechnology for Biofuels
JF - Biotechnology for Biofuels
IS - 1
M1 - 230
ER -
