Response of the Bacterial Metalloproteome to Environmental Conditions Abstract While many life forms are adapted to a narrow range of environmental redox conditions, opportunistic pathogenic bacteria can be highly adaptable to varying environmental conditions. Large changes in oxygen and nutrient availability require a complex suite of sensing, regulation, and biochemical choices in order to allow and maintain cellular growth. Nutritional immunity strategies are important in pathogen-host relationships, where iron and zinc are competed for by pathogen and host. Yet less is known about interactions for scarcer important micronutrients such as cobalt and vitamin B12. This project will examine the response of the Pseudomonas aeruginosa proteome and metalloproteome to varying O2 and metal environmental conditions. Metalloproteomic approaches allow an assessment of the entire soluble metalloprotein pool for each metal simultaneously, answering questions about the deployment of each metal within the metallome, and the interaction between them through metalloenzyme substitutions under varying environmental conditions or genetic manipulations. Given P. aeruginosa's genetic investment in multiple B12-requiring enzymes and their Fe and Zn metalloenzyme substitutes, there is significant room for study on how it manages its metalloenzyme complement and metal homeostasis across redox transitions. This proposal will examine how oxygen is a master controller of metallome composition for P. aeruginosa, impacting the proteome and its metalloenzyme composition. The acquisition of metals and B12 and production of metallophore ligands under oxygen and metal availability conditions will be examined. Major metalloenyzmes will be quantified on an absolute basis to understand the stoichiometric costs for their production across the aerobic to anaerobic gradient. The expected outcome of this research is a detailed understanding of how the metallome of a major opportunistic pathogen is influenced by environmental conditions, which could lead to development of treatment therapies.
Opportunistic pathogens such as Pseudomonas aeruginosa are capable of thriving in both aerobic and anaerobic environments, confronting large changes in redox chemistry that can challenge metal homeostasis and metalloenzyme biosynthesis. The use of the metals cobalt (including as vitamin B12), zinc, iron, and copper are connected through their influence on cellular B12 production and use. This study will determine the response of the Pseudomonas aeruginosa proteome, metalloproteome, and transport systems to varying oxygen and metal conditions, and could provide new understanding of how the metal adaptive strategies of these pathogens contribute to their pathogenicity.
