PhoP is part of the two-component PhoPR system that regulates the expression of virulence genes of Mycobacteria. The goal of this work was to elucidate the role of PhoP in the mechanism that Mycobacterium bovis, the causative agent of bovine tuberculosis, displays upon stress. An analysis of gene expression and acidic growth curves indicated that M. bovis neutralized the external acidic environment by inducing and secreting ammonia. We found that PhoP is essential for ammonia production/secretion and its role in this process seems to be the induction of asparaginase and urease expression. We also demonstrated that the lack of PhoP negatively affected the synthesis of phthiocerol dimycocerosates. This finding is consistent with the role of the lipid anabolism in maintaining the redox environment upon stress in mycobacteria. Altogether the results of this study indicate that PhoP plays an important role in the response mechanisms to stress of M. bovis.

PhoP是两成分PhoPR系统的一部分，该系统调节分枝杆菌毒力基因的表达。这项工作的目的是阐明PhoP在牛结核分枝杆菌（牛结核病的病原体）在压力下表现出的机制中的作用。基因表达和酸性生长曲线的分析表明，牛分枝杆菌通过诱导和分泌氨来中和外部酸性环境。我们发现PhoP对氨的产生/分泌至关重要，其在这一过程中的作用似乎是诱导天冬酰胺酶和脲酶的表达。我们还证明了缺乏PhoP会对phthiocerol dimycocerosates的合成产生负面影响。这一发现与脂质合成代谢在分枝杆菌压力下维持氧化还原环境中的作用一致。总之，这项研究的结果表明，PhoP在牛分支杆菌应激反应机制中发挥了重要作用。