Open AccessCombinatorial Screening for Transgenic Yeasts with High Cellulase Activities in Combination with a Tunable Expression System
Author(s) -
Yoichiro Ito,
Mamoru Yamanishi,
Akinori Ikeuchi,
Chie Imamura,
Takashi Matsuyama
Publication year - 2015
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0144870
Subject(s) - cellulase , expression cassette , gene expression , biology , gene , transgene , yeast , computational biology , genome , genetics , enzyme , biochemistry , recombinant dna , vector (molecular biology)
Combinatorial screening used together with a broad library of gene expression cassettes is expected to produce a powerful tool for the optimization of the simultaneous expression of multiple enzymes. Recently, we proposed a highly tunable protein expression system that utilized multiple genome-integrated target genes to fine-tune enzyme expression in yeast cells. This tunable system included a library of expression cassettes each composed of three gene-expression control elements that in different combinations produced a wide range of protein expression levels. In this study, four gene expression cassettes with graded protein expression levels were applied to the expression of three cellulases: cellobiohydrolase 1, cellobiohydrolase 2, and endoglucanase 2. After combinatorial screening for transgenic yeasts simultaneously secreting these three cellulases, we obtained strains with higher cellulase expressions than a strain harboring three cellulase-expression constructs within one high-performance gene expression cassette. These results show that our method will be of broad use throughout the field of metabolic engineering.