Cytochrome c nitrite reductase from Wolinella succinogenes. Structure at 1.6 A resolution, inhibitor binding, and heme-packing motifs.

摘要: Cytochrome c nitrite reductase catalyzes the 6-electron reduction of to ammonia. This second part respiratory pathway nitrate ammonification is a key step in biological nitrogen cycle. The x-ray structure enzyme from epsilon-proteobacterium Wolinella succinogenes has been solved resolution 1.6 A. It pentaheme c-type cytochrome whose heme groups are packed characteristic motifs that also occur other multiheme cytochromes. Structures W. have obtained with water bound active site iron as well complexes two inhibitors, sulfate and azide, binding modes inhibitory functions differ significantly. highly optimized system found wide range Gram-negative bacteria. reduces both anionic neutral substrates at distal side lysine-coordinated high-spin group, which accessible through different channels, allowing for guided flow reaction educt product. Based on sequence comparison secondary prediction, we demonstrated reductases constitute protein family high structural similarity.