菌株Pigmentiphaga sp. H8中4-羟基苯甲酸羟化酶基因冗余赋予宿主的选择性优势

遗传冗余是生物界的普遍现象，揭示其赋予宿主的选择性优势是生物学研究的热点。然而，学术界对污染物降解基因冗余的研究极少，对其赋予宿主的选择性优势知之甚少，制约了人们对微生物应对复杂污染环境的适应性进化的认识。本项目以生物界普遍存在且具有重要生理功能的4-羟基苯甲酸羟化酶基因作为研究对象，揭示菌株Pigmentiphaga sp. H8中3个冗余的4-羟基苯甲酸羟化酶基因编码酶的酶学特性差异、代谢功能多样性及其赋予宿主的代谢鲁棒性，阐明冗余的4-羟基苯甲酸羟化酶基因赋予宿主应对卤代羟基苯甲酸复合污染的选择性优势；揭示3个4-羟基苯甲酸羟化酶基因的转录调控机制，比较冗余基因在紧缩调控和非紧缩调控下宿主适应性成本的差异，阐明基因紧缩调控在抵消宿主适应性成本中的作用。本项目预期成果将进一步阐释微生物在复杂污染环境下的适应性进化策略，为“遗传冗余赋予宿主选择性优势”的理论提供新的证据。

Genetic redundancy is prevalent in organisms, and its selective advantages brought to hosts have caused great interests of many biologists. However, few studies on the redundancy of pollutant-catabolic genes have been investigated and its selective advantages are still unclear, hindering the understanding of the adaptive evolution of microorganisms to complicatedly polluted environments. p-Hydroxybenzoate hydroxylase gene is prevalent in organisms and has important physiological and metabolic functions. In this project, we will reveal the differences of enzymatic characteristics, the diversity of metabolic functions and the metabolic robustness of the enzymes encoded by the three redundant p-hydroxybenzoate hydroxylase genes in Pigmentiphaga sp. H8, and clarify the selective advantages of the redundancy of these three genes to the host especially in environments complicatedly polluted by halogenated hydroxybenzoates; reveal the transcriptional regulation mechanisms of the three p-hydroxybenzoate hydroxylase genes, compare the fitness cost of the host under constrictive regulation and non-constrictive regulation of these genes, and clarify the effect of the constrictive regulation of these genes on the host to offset the fitness cost of genetic redundancy. The outcomes of the project will further explain the adaptive evolution strategy of microorganisms in the complicatedly polluted environment, and provide new evidence for the theory of "genetic redundancy gives selective advantages to host".