Organisation of Respiratory Electron Transport Chains in Nitrate-Reducing and Nitrifying Bacteria
from: Nitrogen Cycling in Bacteria: Molecular Analysis (Edited by: James W. B. Moir). Caister Academic Press, U.K. (2011)
Nitrogen compounds serve as electron donor and electron acceptor substrates in several modes of microbial respiration such as nitrification, nitrate reduction, denitrification and nitrite ammonification. There are several well-established model bacteria for each of these processes and in many, though not all, cases the various dehydrogenases and reductases involved in the conversion of nitrogen compounds have been thoroughly characterized including the determination of high-resolution structure models. On the other hand, the architecture of complete respiratory electron transport chains is often less-well known, especially with respect to donor:quinone dehydrogenase and quinol:acceptor reductase systems that connect the membranous quinone/quinol pool to the oxidative or reductive part of an electron transport chain. Notably, a rather limited number of redox-active protein modules has evolved that is employed by different bacteria in a versatile manner. Occasionally, bacterial species even display different electron transport chain set-ups despite using the same type of substrate-converting enzyme. This article highlights commonalities and differences in the organisation of bacterial respiratory electron transport chains that are involved in environmentally important N-cycle processes and discusses the relevance of this knowledge in the context of microbial bioenergetics and (meta)genomics read more ...