Expression and characterization of two recombinant manganese-containing catalases (MnCats) from Bacillus pumilus SAFR-032: structural and functional studies, and analysis of binding affinity of metal divalent cations

• Grant number: 12/05441-2
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: October 01, 2012
• End date: January 31, 2014
• Field of knowledge: Biological Sciences - Biochemistry - Chemistry of Macromolecules
• Principal Investigator: Carlos Henrique Inacio Ramos
• Grantee: Daniel Henrique Do Amaral Corrêa
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Excessive hydrogen peroxide (H2O2) is harmful for almost all cell components, and its rapid and efficient removal is of essential importance for aerobic organisms. H2O2 is degraded by catalases, an enzyme able to dismutate the H2O2 to water and molecular oxygen. Nature has evolved three protein families that are able to catalyze this process. Two of these families are heme enzymes comprising the most abundant group found in all kingdoms of life. The third group is a minor bacterial protein family with a dimanganese active site called manganese catalases (MnCats) widely distributed over microbial community, being the oldest H2O2 dismutating catalyst enzymes. Actually, 100 MnCats genes have been annotated in genomic databases, although the assignment of many of these proteins needs to be experimentally verified. Bacillus spores are notoriously resistant to unfavorable conditions such as UV radiation, g-radiation, H2O2, desiccation and chemical disinfection, and B. pumilus SAFR-032, isolated from the Jet Propulsion Lab spacecraft assembly facility (JPL/NASA), survives to these conditions to the extreme. Analysis of the B. pumilus SAFR-032 genome reveals two putative MnCats genes (BPUM_2346 and BPUM_1305), that may have important properties that contribute to the extreme H2O2 resistance of this organism. Our proposal is to express, characterize structurally and functionally, and analyse the binding affinity of different divalent metal cations to these metalloproteins. Additionally, with the expected results from this proposal, we aim to understand the relations between function and structure of MnCats, which may help to design specific inhibitors to prevent diseases in humans, animals and plants related to these enzymes.