开发双诱导双重表达载体,用于调控基因表达和基于 CRISPR 干扰的基因抑制,应用于恶臭假单胞菌 KT2440。

Development of dual-inducible duet-expression vectors for tunable gene expression control and CRISPR interference-based gene repression in Pseudomonas putida KT2440.

机构信息

The Joint BioEnergy Institute, Emeryville, CA, USA.

Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.

出版信息

Microb Biotechnol. 2021 Nov;14(6):2659-2678. doi: 10.1111/1751-7915.13832. Epub 2021 May 19.

Abstract

The development of P. putida as an industrial host requires a sophisticated molecular toolbox for strain improvement, including vectors for gene expression and repression. To augment existing expression plasmids for metabolic engineering, we developed a series of dual-inducible duet-expression vectors for P. putida KT2440. A number of inducible promoters (P , P , P and P ) were used in different combinations to differentially regulate the expression of individual genes. Protein expression was evaluated by measuring the fluorescence of reporter proteins (GFP and RFP). Our experiments demonstrated the use of compatible plasmids, a useful approach to coexpress multiple genes in P. putida KT2440. These duet vectors were modified to generate a fully inducible CRISPR interference system using two catalytically inactive Cas9 variants from S. pasteurianus (dCas9) and S. pyogenes (spdCas9). The utility of developed CRISPRi system(s) was demonstrated by repressing the expression of nine conditionally essential genes, resulting in growth impairment and prolonged lag phase for P. putida KT2440 growth on glucose. Furthermore, the system was shown to be tightly regulated, tunable and to provide a simple way to identify essential genes with an observable phenotype.

摘要

作为一种工业宿主,恶臭假单胞菌的发展需要一套复杂的分子工具来进行菌株改良,包括基因表达和抑制的载体。为了增强代谢工程现有的表达质粒,我们为恶臭假单胞菌 KT2440 开发了一系列双诱导双重表达载体。在不同组合中使用了许多诱导启动子(P1、P2、P3 和 P4)来差异调控单个基因的表达。通过测量报告蛋白(GFP 和 RFP)的荧光来评估蛋白质表达。我们的实验证明了兼容质粒的使用,这是一种在恶臭假单胞菌 KT2440 中共同表达多个基因的有用方法。这些双重载体经过修饰,使用来自巴氏乳球菌(dCas9)和化脓性链球菌(spdCas9)的两种无催化活性 Cas9 变体生成了一个完全可诱导的 CRISPR 干扰系统。开发的 CRISPRi 系统的实用性通过抑制九个条件必需基因的表达得到了证明,这导致恶臭假单胞菌 KT2440 在葡萄糖上的生长受到损害,并且延迟期延长。此外,该系统被证明具有严格的调控性、可调性,并为鉴定具有可观察表型的必需基因提供了一种简单的方法。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/2624/8601191/d1b6860bf6df/MBT2-14-2659-g004.jpg

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