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Poster presented at the 2023 SWOSU Research and Scholarly Activity fair.

Streptococcus sanguinis is a pathobiont that is the leading cause of subacute infective endocarditis (SIE) in humans. Blood transit and attachment to cardiac vegetation is a prerequisite for SIE pathogenesis. While numerous studies have identified cell-surface adhesins in S. sanguinis, many suggested to be involved in SIE remain uncharacterized. One being SSA_0908, a putative ABC-transporter substrate binding proteins (SBP) with homology to CD0837, a SBP from Clostridiodes difficle implicated in host colonization and aromatic amino acid transport. Sequence analysis showed that residues involved in aromatic amino acid ligand binding is highly conserved in SSA_0908. Homology modeling of SSA_0908 revealed a type 1 periplasmic SBP fold with two a-b-a sandwich domains connected via a hinge-loop. The ligand binding pocket at the interface of the sandwich domains shows active site architecture similar to other aromatic amino acid SBP’s. Sequence and structural homology of SSA_0908 to other characterized aromatic amino acid transporters indicated that this protein may be involved in similar function in S. sanguinis. In order to further characterize SSA_0908, we have successfully over-expressed and purified this protein using affinity chromatography. Preliminary crystallization trials resulted in microcrystals in several conditions. We are currently optimizing crystallization conditions to grow diffraction quality crystals.


SWOSU Research, Research fair, Microbiology, Streptococcus, Streptococcus sanguinis, bacteria, bacteriology