Discipline: Biological Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)
Anisha Mittal - Fisk University
Co-Author(s): Adriana Teran, Fisk University, Nashville, TN; RaNashia Boone, Fisk University, Nashville, TN; Lemuel Dent, Meharry Medical College, Nashville, TN; Siddarth Pratap, Meharry Medical College, Nashville, TN; Dana Marshall, Meharry Medical College, Nashville, TN; Steven Damo, Fisk University, Nashville, TN.
Acinetobacter baumannii is a nosocomial pathogen which can infect the respiratory tract, skin, soft tissue, and the urinary tract. The potential global health threat that A. baumannii poses is underscored by the identification of multiple drug resistant (MDR) strains that are impervious to all commercially available antibiotics. Our approach is to understand the molecular mechanisms of antibiotic resistance in A. baumannii with the goal of establishing new strategies for therapeutic intervention. Since pathogens, during infections, are confronted with reactive oxygen species (ROS), prior studies have proposed that enzymes contributing to ROS detoxification, including superoxide dismutases (SODs), can become important virulence factors. SODs, an ROS scavenging mechanism, act as the first line of defense against the harmful effects of ROS by catalyzing the conversion of superoxide anion radicals into hydrogen peroxide and molecular oxygen. Prior studies have identified Superoxide dismutase B (SODB) as an essential virulence factor of A. baumannii. Therefore, SODB represents a potential target for the development of new effective therapeutics to control infections caused by A. baumannii. In this study, we aim to determine the contribution of the SODB enzyme to antibiotic resistance in A. baumannii. To understand the mechanisms causing the resistant nature of A. baumannii, the SODB enzyme was structurally and functionally characterized. The SODB enzyme was expressed recombinantly from E. coli and purified to >95% homogeneity using metal affinity, ion exchange and size-exclusion chromatography. Consistent with other members of the family, SODB is a thermally stable protein with a Tm of 60.2°C determined by differential scanning fluorimetry. We assessed the enzyme’s activity using a water-soluble tetrazolium salt assay and determined the activity of SODB to be 0.2095 µg/U. Additionally, we crystallized SODB and collected diffraction data to 2.0 angstroms resolution. Future work entails determining the crystal structure of SODB and using in silico approaches to identify potential inhibitors. In total, these studies will potentially allow for the development of new strategies and therapeutics to overcome the spread of the MDR pathogen A. baumannii.
Funder Acknowledgement(s): Fisk CREST BioSS Center NSF HRD1547757 ; NIH Award # R25MD010396
Faculty Advisor: Steven Damo, firstname.lastname@example.org
Role: I participated in all aspects of data collection and analysis, with the assistance of the co-authors and supervision of the PI.