Regulation of oxidative phosphorylation: The flexible respiratory network ofParacoccus denitrificans

Abstract

General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 12 May 2018Journal of Bioenergetics and Biomembranes, Vol. 27, No. 5, 1995 Received May 29, 1995 Paracoccus denitrificans is a facultative anaerobic bacterium that has the capacity to adjust its metabolic infrastructure, quantitatively and/or qualitatively, to the prevailing growth condition. In this bacterium the relative activity of distinct catabolic pathways is subject to a hierarchical control. In the presence of oxygen the aerobic respiration, the most efficient way of electron transfer-linked phosphorylation, has priority. At high oxygen tensions P. denitrificans synthesizes an oxidase with a relatively low affinity for oxygen, whereas under oxygen limitation a high-affinity oxidase appears specifically induced. During anaerobiosis, the pathways with lower free energy-transducing efficiency are induced. In the presence of nitrate, the expression of a number of dehydrogenases ensures the continuation of oxidative pbosphorylation via denitrification. After identification of the structural components that are involved in both the aerobic and the anaerobic respiratory networks of P. denitrificans, the intriguing next challenge is to get insight in its regulation. Two transcription regulators have recently been demonstrated to be involved in the expression of a number of aerobic and/or anaerobic respiratory complexes in P. denitrificans. Understanding of the regulation machinery is beginning to emerge and promises much excitement in discovery.KEY WORDS: Respiratory network; multiple oxidases; denitrification; gene regulation; FNR; Paracoccus denitrificans; Escherichia coli. ~TRODUCTIONThe ultimate goal of living organisms is to contribute to a continued existence of their species by means of survival and reproduction. In unicellular organisms, the ability to survive depends on the cell's potential to adapt its metabolism to the available carbon and free-energy sources in its natural habitat, ensuring maintenance and growth. The more such an environment is subject to fluctuations in the supply of these substrates, the higher the demands that are made upon the potential of the cell to adjust its metabolic properties. A profound example of this flexibility is the process of bacterial respiration...

A Mutant of Paracoccus denitrificans with Disrupted Genes Coding for Cytochrome c 550 and Pseudoazurin Establishes These Two Proteins as the In Vivo Electron Donors to Cytochrome cd 1 Nitrite Reductase

“…However, another possible interpretation has been put forward on the basis of the observations made with diethyldithiocarbamate (24). A further indication of the importance of a copper protein in the absence of cytochrome c 550 came from the observation that the mutant grew anaerobically much more poorly in growth media with low copper contents than did the wild-type organism (33,45). Furthermore, the nitrite reductase exhibits activity in vitro with pseudoazurin as an electron donor (29).…”

Cytochromes c 550 , c 552 , and c 1 in the Electron Transport Network of Paracoccus denitrificans : Redundant or Subtly Different in Function?

“…One of the best-studied organisms in that respect is Paracoccus denitrificans. This gram-negative bacterium is able to grow heterotrophically with a variety of organic carbon and free-energy sources, as well as autotrophically, by using hydrogen, or socalled C1 substrates such as methylamine or methanol, as freeenergy sources (2,3,17,41,42,46). The electron transport chain used for aerobic heterotrophic growth possesses a full complement of proteins with counterparts in the mitochondrial respiratory chain (20,41).…”

The nitric oxide regulated nor promoter of Paracoccus denitrificans

“…Transcription from this promoter was detected both aerobically and anaerobically, in vivo and in vitro, and is consistent with previous reports of a low level of activity of the nor promoter in aerobic cultures . Furthermore, there is substantial residual NOR activity in an nnr mutant, and the NorC polypeptide is detectable in aerobically grown cells (van Spanning et al, 1997). All of these observations point towards there being a significant NNR-independent activity of the nor promoter under both aerobic and anaerobic conditions.…”

“…In those organisms that have been studied, expression of the nitrite and NO reductase genes is coordinately regulated by a transcription factor belonging to the FNR (fumarate and nitrate reductase regulator)\CRP (cAMP receptor protein) family (Tosques et al, 1996 ;Arai et al, 1995 ;van Spanning et al, 1997 ;Vollack et al, 1999). In Rhodobacter sphaeroides and Paracoccus denitrificans, there is good evidence that the transcription factor (designated NnrR or NNR, respectively) is activated by NO or a chemical species related to NO (Kwiatkowski & Shapleigh, 1996 ;Tosques et al, 1996 ;van Spanning et al, 1995van Spanning et al, , 1999.…”

“…Transcription of the nor genes is activated by NNR under anaerobic growth conditions in response to NO or a related species (van Spanning et al, 1995. NNR also activates the transcription of the divergent nirI and nirS genes that are required for nitrite reductase activity (van Spanning et al, 1997). FnrP appears to be a true orthologue of FNR, in that it contains the cysteine residues that are conserved in FNR-like proteins and are believed to provide ligands to an oxygen\redox-sensitive iron-sulphur cluster.…”