This application aims to understand the mechanisms and pathways that the human pathogens Staphylococcus aureus and Pseudomonas aeruginosa use to counter oxidative stress produced by host immune response. Staphylococcus aureus is a human pathogen responsible for most wound and hospital-acquired infections and is responsible for the highest mortality of any infectious diseases in the United States. The extensive use of antibiotics to treat S. aureus infections has led to the emergence and rapid spread of highly virulent, drug-resistant S. aureus strains (MRSA) worldwide. Virulence suppression provides an alternative strategy to effectively reduce pathogenic potential without asserting selective pressure for developing resistances. My laboratory has identified new global regulatory proteins that control the virulence of S. aureus. Mechanistic studies indicate that these proteins possess redox-active Cys residues to sense reactive oxygen species (ROS). Human innate immune response produces high concentrations of ROS to counter bacterial infections. Therefore, our discovery suits well that a pathogen inside a human host uses oxidation-sensing mechanisms to sense the host immune response and regulate a global change of its properties including virulence and metabolisms. We employ an advanced chemical proteomic technology, based on activity-based protein profiling (ABPP) methods, to quantitatively profile functional cysteines to profile oxidation-sensitive cysteines in the proteomes of S. aureus and P. aeruginosa. Besides identifying additional regulatory proteins that are redox active, we also aim to discover major metabolic pathways that are dramatically affected by ROS treatment. A global view of how these pathogens respond to oxidative stress will emerge from the proposed program of studies with key virulence determinants identified and characterized. Other than Cys-oxidation, we have made a surprising new discovery that the functional Cys residues in many of these proteins that are oxidation sensitive can also be phosphorylated. The Cys-phosphorylated form of the regulatory protein correlates to the low virulence state of the pathogen just like the Cys-oxidized form of these regulators. Thus, these master switches possess multiple regulatory mechanisms to sense and respond to diverse host and/or environmental signals including oxidative stress. The discovery that Cys-phosphorylation plays important roles in biological regulation is unprecedented and is itself fundamentally interesting. The underlying mechanism and pathways will be elucidated.
Staphylococcus aureus and Pseudomonas aeruginosa cause a major percentage of infections in the United States. The proposed research will uncover the mechanisms and pathways that these bacteria use to counter oxidative stress produced from host immune response. An advanced chemical activity-based protein profiling (ABPP) method will be employed to quantitatively profile functional cysteines in the proteomes of these human pathogens.
|Tirumuru, Nagaraja; Zhao, Boxuan Simen; Lu, Wuxun et al. (2016) N(6)-methyladenosine of HIV-1 RNA regulates viral infection and HIV-1 Gag protein expression. Elife 5:|
|Ji, Quanjiang; Chen, Peter J; Qin, Guangrong et al. (2016) Structure and mechanism of the essential two-component signal-transduction system WalKR in Staphylococcus aureus. Nat Commun 7:11000|
|Deng, Xin; Chen, Kai; Luo, Guan-Zheng et al. (2015) Widespread occurrence of N6-methyladenosine in bacterial mRNA. Nucleic Acids Res 43:6557-67|
|Deng, Xin; Liang, Haihua; Chen, Kai et al. (2014) Molecular mechanisms of two-component system RhpRS regulating type III secretion system in Pseudomonas syringae. Nucleic Acids Res 42:11472-86|
|Deng, Xin; Liang, Haihua; Ulanovskaya, Olesya A et al. (2014) Steady-state hydrogen peroxide induces glycolysis in Staphylococcus aureus and Pseudomonas aeruginosa. J Bacteriol 196:2499-513|
|Ji, Quanjiang; Zhao, Boxuan Simen; He, Chuan (2013) A highly sensitive and genetically encoded fluorescent reporter for ratiometric monitoring of quinones in living cells. Chem Commun (Camb) 49:8027-9|
|Deng, Xin; Weerapana, Eranthie; Ulanovskaya, Olesya et al. (2013) Proteome-wide quantification and characterization of oxidation-sensitive cysteines in pathogenic bacteria. Cell Host Microbe 13:358-70|
|Ji, Quanjiang; Zhang, Liang; Jones, Marcus B et al. (2013) Molecular mechanism of quinone signaling mediated through S-quinonization of a YodB family repressor QsrR. Proc Natl Acad Sci U S A 110:5010-5|
|Sun, Fei; Liang, Haihua; Kong, Xiangqian et al. (2012) Quorum-sensing agr mediates bacterial oxidation response via an intramolecular disulfide redox switch in the response regulator AgrA. Proc Natl Acad Sci U S A 109:9095-100|
|Brugarolas, Pedro; Movahedzadeh, Farahnaz; Wang, Yuehong et al. (2012) The oxidation-sensing regulator (MosR) is a new redox-dependent transcription factor in Mycobacterium tuberculosis. J Biol Chem 287:37703-12|
Showing the most recent 10 out of 31 publications