Hughes Jonathan G, Zhang Xiangsheng, Parales Juanito V, Ditty Jayna L, Parales Rebecca E
Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California Davis, Davis, California, USA.
Jiangsu Provincial Key Laboratory of Coastal Wetland Bioresources and Environmental Protection, Yancheng Teachers University, Yancheng, PR China.
Microbiology (Reading). 2017 Oct;163(10):1490-1501. doi: 10.1099/mic.0.000533. Epub 2017 Sep 28.
Soil bacteria such as pseudomonads are widely studied due to their diverse metabolic capabilities, particularly the ability to degrade both naturally occurring and xenobiotic aromatic compounds. Chemotaxis, the directed movement of cells in response to chemical gradients, is common in motile soil bacteria and the wide range of chemicals detected often mirrors the metabolic diversity observed. Pseudomonas putida F1 is a soil isolate capable of chemotaxis toward, and degradation of, numerous aromatic compounds. We showed that P. putida F1 is capable of degrading members of a class of naturally occurring aromatic compounds known as hydroxycinnamic acids, which are components of lignin and are ubiquitous in the soil environment. We also demonstrated the ability of P. putida F1 to sense three hydroxycinnamic acids: p-coumaric, caffeic and ferulic acids. The chemotaxis response to hydroxycinnamic acids was induced during growth in the presence of hydroxycinnamic acids and was negatively regulated by HcaR, the repressor of the hydroxycinnamic acid catabolic genes. Chemotaxis to the three hydroxycinnamic acids was dependent on catabolism, as a mutant lacking the gene encoding feruloyl-CoA synthetase (Fcs), which catalyzes the first step in hydroxycinnamic acid degradation, was unable to respond chemotactically toward p-coumaric, caffeic, or ferulic acids. We tested whether an energy taxis mutant could detect hydroxycinnamic acids and determined that hydroxycinnamic acid sensing is mediated by the energy taxis receptor Aer2.
诸如假单胞菌之类的土壤细菌因其多样的代谢能力，特别是降解天然存在的和外源性芳香族化合物的能力而受到广泛研究。趋化性，即细胞响应化学梯度的定向运动，在可运动的土壤细菌中很常见，检测到的广泛化学物质常常反映出所观察到的代谢多样性。恶臭假单胞菌F1是一种土壤分离菌株，能够对多种芳香族化合物进行趋化并降解它们。我们发现恶臭假单胞菌F1能够降解一类天然存在的芳香族化合物——羟基肉桂酸的成员，羟基肉桂酸是木质素的组成成分，在土壤环境中普遍存在。我们还证明了恶臭假单胞菌F1能够感知三种羟基肉桂酸：对香豆酸、咖啡酸和阿魏酸。在羟基肉桂酸存在下生长期间，对羟基肉桂酸的趋化反应被诱导，并且受到羟基肉桂酸分解代谢基因的阻遏物HcaR的负调控。对这三种羟基肉桂酸的趋化性依赖于分解代谢，因为缺乏编码阿魏酰辅酶A合成酶（Fcs）的基因的突变体无法对香豆酸、咖啡酸或阿魏酸作出趋化反应，Fcs催化羟基肉桂酸降解的第一步。我们测试了能量趋化突变体是否能够检测羟基肉桂酸，并确定羟基肉桂酸的感知是由能量趋化受体Aer2介导的。
