Intracellular expression of Vitreoscilla hemoglobin improves S-adenosylmethionine production in a recombinant Pichia pastoris |
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Authors: | Huaxin Chen Ju Chu Siliang Zhang Yingping Zhuang Jiangchao Qian Yonghong Wang Xiaoqing Hu |
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Institution: | (1) State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 200237 Shanghai, People’s Republic of China;(2) Present address: East China University of Science and Technology, P.O. Box 329#, 130 Meilong Rd., Shanghai, People’s Republic of China |
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Abstract: | To develop an efficient way to produce S-adenosylmethionine (SAM), methionine adenosyltransferase gene (mat) from Streptomyces spectabilis and Vitreoscilla hemoglobin gene (vgb) were coexpressed intracellularly in Pichia pastoris, both under control of methanol-inducible promoter. Expression of mat in P. pastoris resulted in about 27 times higher specific activity of methionine adenosyltransferase (SMAT) and about 19 times higher SAM
production relative to their respective control, suggesting that overexpression of mat could be used as an efficient method for constructing SAM-accumulating strain. Under induction concentration of 0.8 and 2.4%
methanol, coexpression of vgb improved, though to different extent, cell growth, SAM production, and respiratory rate. However, the effects of VHb on SAM
content (specific yield of SAM production) and SMAT seemed to be methanol concentration-dependent. When cells were induced
with 0.8% methanol, no significant effects of VHb expression on SAM content and specific SMAT could be detected. When the
cells were induced with 2.4% methanol, vgb expression increased SAM content significantly and depressed SMAT remarkably. We suggested that under our experimental scheme,
the presence of VHb might improve ATP synthesis rate and thus improve cell growth and SAM production in the recombinant P. pastoris. |
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Keywords: | S-adenosylmethionine Vitreoscilla hemoglobin Pichia pastoris Methionine adenosyltransferase |
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