Analysis of Salmonella PhoP/PhoQ regulation by dimethyl-SRM-based quantitative proteomics

Hu, Li-Zhi; Zhang, Wei-Ping; Zhou, Mao-Tian; Han, Qiang-Qiang; Gao, Xiao-Li; Zeng, Hao-Long; Guo, Lin

Analysis of Salmonella PhoP/PhoQ regulation by dimethyl-SRM-based quantitative proteomics

2016

SRM (selected reaction monitoring), a tandem mass spectrometry-based method characterized by high repeatability and accuracy, is an effective tool for the quantification of predetermined proteins. In this study, we built a time-scheduled dimethyl-SRM method that can provide the precise relative quantification of 92 proteins in one run. By applying this method to the Salmonella PhoP/PhoQ two-component system, we found that the expression of selected PhoP/PhoQ-activated proteins in response to Mg²⁺ concentrations could be divided into two distinct patterns. For the time-course SRM experiment, we found that the dynamics of the selected PhoP/PhoQ-activated proteins could be divided into three distinct patterns, providing a new clue regarding PhoP/PhoQ activation and regulation. Moreover, the results for iron homeostasis proteins in response to Mg²⁺ concentrations revealed that the PhoP/PhoQ two-component system may serve as a repressor for iron uptake proteins. And ribosomal protein levels clearly showed a response to different Mg²⁺ concentrations and to time.

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