Structural adaptation of active center channels of octaheme nitrite reductases from the haloalkaliphilic bacteria Thioalkalivibrio nitratireducens to a proton deficit

Study of the adaptation mechanisms of proteins from extremophiles paves the way for the development of new biocatalysts that are resistant to extreme conditions. Here, we studied the structural adaptation of active center channels of octaheme nitrite reductase from the haloalkophilic bacterium Thioalkalivibrio nitratireducens (TvNiR) to high pH. Comparative analysis of the structures of octaheme nitrite reductases adapted to different environmental conditions revealed unique adaptation mechanisms for TvNiR, which play an important role in binding rare protons and substrate and product migration in the active-site channels.