SSA_0809 is a Homotrimeric, Reactive Intermediate Deaminase A (RidA) from an Opportunistic Pathogen, Streptococcus sanguinis
Poster presented at the 2023 SWOSU Research and Scholarly Activity fair.
Pictured here is student Adreana Aquino
Reactive intermediate deaminase A (RidA) is a low-molecular weight protein in YjgF/YER057c/UK114 superfamily. The archetypal RidA subfamily is involved in amino acid metabolism and shown to catalyze the neutralization of toxic 2-amino acrylate (2AA) intermediates produced during amino acid catabolism. In Salmonella enterica, mutants lacking ridA exhibit physiological defects from the antagonistic interaction of 2AA with pyridoxal phosphate (PLP)-dependent enzymes. The importance of RidA and the incomplete understanding of metabolic networks affected by RidA led us to investigate its role in Streptococcus sanguinis, an opportunistic pathogen and the leading cause of subacute infective endocarditis in humans. BLAST analysis of S. sanguinis genome revealed a protein SSA_0809 with 50% identity to RidA from S. enterica. Biochemical studies on S. sanguinis SSA_0809, henceforth SsRidA, revealed its capacity of accelerating 2AA neutralization to pyruvate. To better understand SsRidA activity, the first crystal structure in a holoenzyme confirmation was solved at 1.97Å. The overall structure of SsRidA revealed a homotrimeric arrangement with active sites formed at the monomer interfaces, typical for this family. Active site electron density revealed the presence of ligand in only one active site leaving two active sites unoccupied. This incomplete ligand occupancy in SsRidA is still under investigation.
SWOSU Research, Research fair, Microbiology, Streptococcus, Streptococcus sanguinis, bacteria, bacteriology