Codon optimization prevents premature polyadenylation of heterologously-expressed cellulases from termite-gut symbionts in Aspergillus oryzae.
To achieve high expression of glycoside hydrolase family 45 endoglucanase (RsSym45EG1) from a symbiotic protist of the termite Reticulitermes speratus, synthetic sequence RsSym45eg1-co, in which the codon usage was adjusted to that of the highly-expressed tef1 gene encoding translation elongation factor 1alpha, was prepared and introduced into A. oryzae. The transcript level of RsSym45eg1-co was 1.8-fold higher than that of RsSym45eg1. In cells harboring RsSym45eg1, but not RsSym45eg1-co, truncated transcripts in which the coding region was prematurely terminated and followed by a poly A chain were found. The production of endoglucanase in the culture supernatant was improved by codon optimization. Truncated transcripts were also found when cellobiohydrolase and beta-glucosidase from R. speratus symbionts were expressed, and the transcript level of the former was increased by codon-optimization. Our findings suggest that premature polyadenylation frequently occurs in heterologous protein expression in A. oryzae, which might result in the poor yield of expressed proteins.
Sasaguri
Shiho
S
Department of Biotechnology, The University of Tokyo, Tokyo, Japan.
Maruyama
Jun-ichi
J
Moriya
Shigeharu
S
Kudo
Toshiaki
T
Kitamoto
Katsuhiko
K
Arioka
Manabu
M
D000818:Animals; D001236:Aspergillus oryzae / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D044602:Cellulases / Q000235:genetics / Q000378:metabolism*; D003062:Codon / Q000235:genetics / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000378:metabolism / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D020049:Isoptera / Q000382:microbiology*; D008969:Molecular Sequence Data; D026723:Polyadenylation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D013559:Symbiosis
D003062:Codon; D011994:Recombinant Proteins; D044602:Cellulases