title: The role and regulation of catalase in respiratory tract opportunistic bacterial pathogens.
abstract: Respiratory tract bacterial pathogens are the etiologic agents of a variety of illnesses. The ability of these bacteria to cause disease is imparted through survival within the host and avoidance of pathogen clearance by the immune system. Respiratory tract pathogens are continually bombarded by reactive oxygen species (ROS), which may be produced by competing bacteria, normal metabolic function, or host immunological responses. In order to survive and proliferate, bacteria have adapted defense mechanisms to circumvent the effects of ROS. Bacteria employ the use of anti-oxidant enzymes, catalases and catalase-peroxidases, to relieve the effects of the oxidative stressors to which they are continually exposed. The decomposition of ROS has been shown to provide favorable conditions in which respiratory tract opportunistic bacterial pathogens such as Haemophilus influenzae, Mycobacterium tuberculosis, Legionella pneumophila, and Neisseria meningitidis are able to withstand exposure to highly reactive molecules and yet survive. Bacteria possessing mutations in the catalase gene have a decreased survival rate, yet may be able to compensate for the lack of catalatic activity if peroxidatic activity is present. An incomplete knowledge of the mechanisms by which catalase and catalase-peroxidases are regulated still persists, however, in some bacterial species, a regulatory factor known as OxyR has been shown to either up-regulate or down-regulate catalase gene expression. Yet, more research is still needed to increase the knowledge base in relation to this enzyme class. As with this review, we focus on major respiratory tract opportunistic bacterial pathogens in order to elucidate the function and regulation of catalases. The importance of the research could lead to the development of novel treatments against respiratory bacterial infections.
authors.affiliation: West Chester University of Pennsylvania, Department of Biology, 750 South Church Street, West Chester, PA 19383, USA. Electronic address: me632265@wcupa.edu.
authors.forename: Mia M
authors.initials: MM
authors.lastname: Eason
authors.affiliation: West Chester University of Pennsylvania, Department of Biology, 750 South Church Street, West Chester, PA 19383, USA. Electronic address: xfan@wcupa.edu.
authors.forename: Xin
authors.initials: X
authors.lastname: Fan
mesh_terms: D000222:Adaptation, Physiological; D001419:Bacteria / Q000201:enzymology* / Q000302:isolation & purification; D002374:Catalase / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D050296:Microbial Viability; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism* / Q000633:toxicity*; D012141:Respiratory Tract Infections / Q000382:microbiology*
chemical_list: D017382:Reactive Oxygen Species; D002374:Catalase
keywords: Catalase; Reactive oxygen species; Respiratory opportunistic pathogen