College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China.
College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China.
Biotechnol Adv. 2017 Jul;35(4):505-511. doi: 10.1016/j.biotechadv.2017.03.008. Epub 2017 Mar 23.
Agrobacterium tumefaciens, a soil-born phytopathogenic bacterium, is well known as a nature's engineer due to its ability to genetically transform the host by transferring a DNA fragment (called T-DNA) from its Ti plasmid to host-cell genome. To combat the harsh soil environment and seek the appropriate host, A. tumefaciens can sense and be attracted by a large number of chemical compounds released by wounded host. As a member of α-proteobacterium, A. tumefaciens has a chemotaxis system different from that found in Escherichia coli, since many chemoattractants for A. tumefaciens chemotaxis are virulence (vir) inducers. However, advances in the study of the chemotaxis paradigm, E. coli chemotaxis system, have provided enough information to analyze the A. tumefaciens chemotaxis. At low concentration, chemoattractants elicit A. tumefaciens chemotaxis and attract the species to the wound sites of the host. At high concentration, chemoattractants induce the expression of virulence genes and trigger T-DNA transfer. Recent studies on the VirA and ChvE of the vir-induction system provide some evidences to support the crosstalk between chemotaxis and vir-induction. This review compares the core components of chemotaxis signaling system of A. tumefaciens with those observed in other species, discusses the connection between chemotaxis and vir-induction in A. tumefaciens, and proposes a model depicting the signaling crosstalk between chemotaxis and vir-induction.
根癌农杆菌是一种土壤来源的植物病原细菌，由于其能够通过将来自 Ti 质粒的 DNA 片段（称为 T-DNA）转移到宿主细胞基因组中来遗传转化宿主，因此被称为自然界的工程师。为了适应恶劣的土壤环境并寻找合适的宿主，根癌农杆菌可以感知并被宿主释放的大量化学物质所吸引。作为α变形菌的一员，根癌农杆菌的趋化系统与大肠杆菌中的趋化系统不同，因为许多根癌农杆菌趋化作用的化学引诱物是毒力（vir）诱导物。然而，趋化作用范例、大肠杆菌趋化作用系统的研究进展提供了足够的信息来分析根癌农杆菌的趋化作用。在低浓度下，化学引诱物会引发根癌农杆菌的趋化作用，并吸引该物种向宿主的创伤部位移动。在高浓度下，化学引诱物会诱导毒力基因的表达，并触发 T-DNA 转移。最近对毒力诱导系统中的 VirA 和 ChvE 的研究提供了一些证据，支持趋化作用和毒力诱导之间的串扰。本文比较了根癌农杆菌趋化作用信号系统的核心组成部分与其他物种中的观察结果，讨论了根癌农杆菌中趋化作用和毒力诱导之间的联系，并提出了一个描述趋化作用和毒力诱导之间信号串扰的模型。
