Assembly of Respiratory Proteins of the Nitrogen Cycle
Shilpa Bali and Stuart J. Ferguson
from: Nitrogen Cycling in Bacteria: Molecular Analysis (Edited by: James W. B. Moir). Caister Academic Press, U.K. (2011)
The respiratory reactions of the nitrogen cycle are those of denitrification, the successive reductions of nitrate, nitrite, nitric oxide and nitrous oxide to nitrogen gas, and those of nitrification, oxidation of ammonium first to nitrite and then to nitrate. These reactions are catalysed by enzymes containing one or more of the cofactors, heme (non-covalent as in b-type hemes, or covalent as in c-type hemes), iron sulphur, molybdenum and copper centres. With the exception of molybdenum, these redox active cofactors are also integral to the operation of the respiratory chain systems that deliver electrons to and from the individual enzymes. This chapter gives an overview of current knowledge about how each of these cofactor types is attached to their respective apo-proteins, in the context that many of the proteins are located on the periplasmic side of the membrane and delivery to that compartment is either as an unfolded protein, and thus mediated by the sec system, or as a folded protein and thus facilitated by the tat system read more ...