Analysis of the Interactions Between Thiocyanate Dehydrogenase and Thioredoxin-Like Protein Using Molecular Modeling

Thiocyanate dehydrogenase (TcDH) and thioredoxin like protein (TLP) play an important role in metabolism of some sulfur-oxidizing bacteria (SOB). TcDH catalyzes oxidative thiocyanate conversion into cyanate, elemental sulfur, and two reducing equivalents without involvement of molecular oxygen. The gene of thioredoxin-like protein (TLP) can be found adjacent to the gene of TcDH for some SOB. The co-evolving residues (correlating mutations) for TcDH and TLP sequences for these SOB were determined using bioinformatic analysis. The models of TcDH and TLP from Thiohalobacter thiocyanaticus HRh1 were obtained by homology modeling. Macromolecular docking of the TcDH and TLP models confirmed the positions of some co-evolving residues in interacting interfaces. Analysis of the protein complexes revealed the 2 possible binding sites involved in interaction between TcDH and TLP. We identified the specific residues in TcDH and TLP that stabilize the interactions.