Transcription levels of key metabolic genes are the cause for different glucose utilization pathways in E-coli B (BL21) and E-coli K (JM109)
Transcription levels of key metabolic genes are the cause for different glucose utilization pathways in E-coli B (BL21) and E-coli K (JM109)
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DOI：
10.1016/j.jbiotec.2003.10.038
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发表时间：
2004-04-08
影响因子：
4.1
通讯作者：
Shiloach, J
中科院分区：
文献类型：
--
作者：
Phue, JN;Shiloach, J
醋酸盐积累是在大肠杆菌高密度好氧培养中观察到的常见问题。以前的报道已经假设乙醛分流在低醋酸盐产生菌E.coliBL21中是活跃的，而在高醋酸盐产生菌E.coliJM109中是不活跃的。通过将来自统一标记的葡萄糖的(13)结合到TCA循环中间体中，这一假设得到了进一步的强化。通过Northern印迹分析，本研究证实了乙醛酸途径在大肠杆菌JM109中失活的原因是异柠檬酸裂解酶(ACEA)和苹果酸合成酶(ACEB)没有明显的转录，以及异柠檬酸裂解酶抑制物(OR)的转录。在大肠杆菌BL21中，由于ACEA和ACEB的结构性转录和OR的无转录，乙醛酸途径是活跃的。此外，这两个菌株在乙酰辅酶A合成酶(ACS)、磷酸转乙酰基酶-醋酸激酶(PTA-ackA)和丙酮酸氧化酶(PoxB)途径的转录上也存在差异。Acs的转录在大肠杆菌BL21中较高，在大肠杆菌JM109中较低，而poxB的转录则相反。爱思唯尔出版公司(Elsevier B.V.)
Acetate accumulation is a common problem observed in aerobic high cell density cultures of Escherichia coli. It has been hypothesized in previous reports that the glyoxylate shunt is active in E. coli BL21, the low acetate producer, and inactive in E. coli JM109, the high acetate producer. This hypothesis was further strengthened by incorporating (13) from uniformly labeled glucose into TCA cycle intermediates. Using northern blot analyses, the current report demonstrates that the reason for the inactivity of the glyoxylate pathway in E. coli JM109 is the no apparent transcription of isocitrate lyase (aceA) and malate synthase (aceB), and transcription of the isocitrate lyase repressor (OR). The reverse is seen in E. coli BL21 where the glyoxylate pathway is active due to constitutive transcription of aceA and aceB and no transcription of the OR. In addition, there is a difference between the two strains in the transcription of the acetyl-CoA synthetase (acs), phosphotransacetylase-acetate kinase (pta-ackA) pathway, and pyruvate oxidase (poxB), pathway. The transcript of acs is higher in E. coli BL21 and lower in the E. coli JM109, while the reverse is true for poxB transcription. Published by Elsevier B.V.