Coexpression of Vitreoscilla Hemoglobin Reduces the Toxic Effect of Expression of D-Amino Acid Oxidase in E. coli

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• 作者：Liang-Jung Chien ; Jyh-Ming Wu ; I-Ching Kuan ; and Cheng-Kang Lee
• 刊名：Biotechnology Progress
• 出版年：2004
• 出版时间：October 2004
• 年：2004
• 卷：20
• 期：5
• 页码：1359 - 1365
• 全文大小：135K
• 年卷期：v.20,no.5(October 2004)
• ISSN：1520-6033

文摘

Expression of the gene (daao) encoding D-amino acid oxidase (DAAO) in Escherichiacoli typically results in a marked decrease of cell viability, and it has generally beenassumed that the consumption of intracellular D-alanine by DAAO is responsible forthis effect. Vitreoscilla hemoglobin (VHb) gene (vgb) was coexpressed with Rhodosporidium toruloides D-amino acid oxidase in E. coli BL21(DE3) and BL21(DE3)pLysS,expression hosts differing in the stringency of suppressing basal transcription. Notonly was the toxic effect of DAAO on cell growth relieved but also the pronounced celllysis of BL21(DE3)pLysS caused by the expression of DAAO was prevented bycoexpressing VHb with DAAO. As a result of the higher cell density achieved, DAAOactivity about 1.5-fold higher than that of DAAO-expressing control strains could beobtained by DAAO/VHb-coexpressing strains. The relieving effect of VHb on DAAOtoxicity resulted from its oxygen-binding ability. The low availability of free intracellular oxygen reduced DAAO activity and consequently its toxicity.