Single point mutation in the transcriptional regulator PnpR renders Pseudomonas sp. strain WBC-3 capable of utilizing 2-chloro-4-nitrophenol
Single point mutation in the transcriptional regulator PnpR renders Pseudomonas sp. strain WBC-3 capable of utilizing 2-chloro-4-nitrophenol
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转录调节因子 PnpR 中的单点突变导致假单胞菌 (Pseudomonas sp.)。
DOI：
10.1016/j.ibiod.2019.104732
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发表时间：
2019-09-01
影响因子：
4.8
通讯作者：
Zhou, Ning-Yi
中科院分区：
文献类型：
--
作者：
Deng, Shi-Kai;Zhang, Wen-Mao;Zhou, Ning-Yi
假单胞菌属菌株WBC-3矿化对硝基苯酚(PNP)作为生长底物。负责PNP降解的基因由3个操纵子组成：pnpA、pnpB和pnpCDEFG。2-氯-4-硝基苯酚(2C4NP)作为一种氯化PNP，是PNP 4-单加氧酶PnpA的底物，但菌株WBC-3不能利用2C4NP。LysR型转录调节因子(LTTR)PnpR在PNP刺激下激活3个分解代谢操纵子的表达。此外，除了PNP外，另一个LTTR PnpM还响应2C4NP来启动pnpCDEFG操纵子的表达。通过长期定向进化选择，获得了生长在2C4NP上的菌株WBC-3的自发突变株。2C4NP(+)株PnpR基因第6密码子存在单一突变，半胱氨酸取代丝氨酸。突变体PnpR(S6C)以一种几乎构成的方式驱动pnpA和pnpB操纵子的非PNP表达，但在加入诱导剂后允许更高水平的诱导。然而，pnpCDEFG操纵子的表达与活性PnpR(S6C)一样仍然依赖于PNP。当将pnpR(S6C)等位基因导入pnpR缺失的WBC-3突变株时，相应的菌株获得了在2C4NP上生长的能力，但仍然能够利用PNP进行生长。
Pseudomonas sp. strain WBC-3 mineralizes para-nitrophenol (PNP) as a growth substrate. The genes responsible for PNP degradation constitute 3 operons: pnpA, pnpB, and pnpCDEFG. As a chlorinated PNP, 2-chloro-4-nitrophenol (2C4NP) serves as a substrate for the PNP 4-monooxygenase PnpA; however, strain WBC-3 is unable to utilize 2C4NP. The LysR-type transcriptional regulator (LTTR) PnpR activates the expression of the 3 catabolic operons in response to PNP. Furthermore, an additional LTTR PnpM responds to 2C4NP other than PNP to initiate the expression of pnpCDEFG operon. Using a long-term directed evolution selection, spontaneous mutants of strain WBC-3 that grew on 2C4NP were obtained. The 2C4NP(+) strains had single mutation in codon 6 of the gene encoding PnpR, with substitution of cysteine for serine. The variant PnpR(S6C) drove the PNP-independent expression of pnpA and pnpB operons in an almost constitutive manner but allowed higher levels of induction upon addition of inducers. However, expression of pnpCDEFG operon was still PNP-dependent together with active PnpR(S6C). When the pnpR(S6C) allele was introduced into a pnpR-deleted WBC-3 mutant, the corresponding strain acquired the ability to grow on 2C4NP but was still able to utilize PNP for growth.