Production and secretion patterns of cloned glucoamylase in plasmid-harboring and chromosome-integrated recombinant yeasts employing an SUC2 promoter |
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Authors: | Hyung Joon Cha Hee Jeong Chae Suk Soon Choi Young Je Yoo |
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Institution: | (1) Department of Chemical Engineering & Division of Molecular and Life Sciences, Pohang University of Science and Technology, 790-784 Pohang, Korea;(2) Department of Food Technology, Hoseo University, 336-795 Asan, Korea;(3) Department of Paper Technology, Yongin Songdam College, 449-040 Yongin, Korea;(4) Division of Chemical Engineering, Seoul National University, 151-742 Seoul, Korea |
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Abstract: | To understand the differences in production and secretion patterns between plasmid-harboring and chromosome-integrated recombinant
yeasts, the two recombinant Saccharomyces cerevisiae yeasts, containing the structural glucoamylase STA gene and the SUC2 promoter, were investigated. Both systems were regulated by glucose concentration in the culture broth. First, the glucoamylase
activity per gene copy number of the chromosome-integrated recombinant yeast was 2.8- to 5.6-fold higher than that of the
plasmid-harboring recombinant yeast. Overburdened owing to high copy number, the plasmid-harboring recombinant yeast gave
lower glucoamylase activity per gene copy number. Second, the efficiency of signal sequence was compared; the secretion efficiency
of glucoamylase in the plasmid-harboring recombinant yeast was higher than that in the chromosome-integrated recombinant yeast
at 96 h of cultivation (74 vs 65%). We postulated that the higher level of secretion efficiency of the plasmid-harboring recombinant
yeast resulted because the production level did not reach the capacity of the secretory apparatus of the host yeast. However,
the specific secretion rate was much higher in the chromosome-integrated recombinant yeast even though the final secretion
efficiency was lower. The lower secretion rate in the plasmid-harboring recombinant yeast could be explained by an adverse
effect caused by higher production rate. Finally, the optimal glucose concentration for glucoamylase production in the chromosome-integrated
recombinant yeast culture was lower than that in the plasmid-harboring recombinant yeast culture owing to gene dosage effect. |
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Keywords: | Plasmid-harboring recombinant yeast chromosome-integrated recombinant yeast SUC2 promoter glucoamylase production secretion |
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