Almeida, R. M., S. Dell'acqua, I. Moura, S. R. Pauleta, and JJG Moura CHAPTER 11: Electron Transfer and Molecular Recognition in Denitrification and Nitrate Dissimilatory Pathways. Eds. I. Moura, JJG Moura, L. B. Maia, C. D. Garner, and S. R. Pauleta. Vol. 2017-January. RSC Metallobiology, 2017-January. Royal Society of Chemistry, 2017.
AbstractThe electron transfer pathways for the enzymes involved in the four sequential steps of the denitrification pathway are reviewed. In addition, brief information on the electron transfer events is also provided on two enzymes that participate in the dissimilatory nitrate reduction to ammonia. The two main aspects discussed are the intra- and inter-molecular electron transfer pathways and the molecular recognition processes involving the redox partners. When available, information on the residues that are involved in these pathways is given, and their role in electron transfer and/or the formation of the transient electron transfer complexes is discussed. © The Royal Society of Chemistry 2017.
Moura, I., L. B. Maia, S. R. Pauleta, and JJG Moura CHAPTER 1: A Bird's Eye View of Denitrification in Relation to the Nitrogen Cycle. Eds. I. Moura, JJG Moura, L. B. Maia, C. D. Garner, and S. R. Pauleta. Vol. 2017-January. RSC Metallobiology, 2017-January. Royal Society of Chemistry, 2017.
AbstractThis book is devoted to denitrification, an anaerobic process that is used by a wide range of bacteria for energy generation. The overall process involves nitrate, which is present in soil or water, being reduced to gaseous dinitrogen. This initial chapter aims to place denitrification in the larger context of the nitrogen biogeochemical cycle (a bird's eye view). Detailed topics are developed through the many following contributions. Denitrification is a landscape for probing the structures, functions and mechanisms of action of a wide range of highly specialised metalloenzymes. These carry out, sequentially, four oxo-transfer reactions: NO3 - → NO2 - → NO → N2O → N2. The environmental implications of these processes are of particular relevance. Nitrate accumulation and the release of nitrous oxide into the atmosphere due to the excessive use of fertilisers in agriculture are examples of two environmental problems in which denitrification plays a central role. © The Royal Society of Chemistry 2017.
Pauleta, S. R., C. Carreira, and I. Moura CHAPTER 7: Insights into Nitrous Oxide Reductase. Eds. I. Moura, JJG Moura, L. B. Maia, C. D. Garner, and S. R. Pauleta. Vol. 2017-January. RSC Metallobiology, 2017-January. Royal Society of Chemistry, 2017.
AbstractNitrous oxide reductase is the enzyme that catalyses the last step of the denitrification pathway, reducing nitrous oxide to dinitrogen gas. This enzyme is a functional homodimer with two copper centres, CuA and a "CuZ centre", located in different domains. The CuA centre is the electron transferring centre, while the catalytic centre is the "CuZ centre", a unique metal centre in biology - a tetranuclear copper centre with a μ4-bridging sulphide. The enzyme has been isolated with the "CuZ centre" in two different forms, CuZ(4Cu2S) and CuZ∗(4Cu1S), with the first presenting an additional μ2-sulphur atom as a bridging ligand between CuI and CuIV of the "CuZ centre", whereas the second form was identified as a water-derived molecule. Spectroscopic analysis of CuZ∗(4Cu1S), together with computational studies, indicated that there is a hydroxide bound to CuI. Genomic analysis has identified the presence of two different types of nitrous oxide reductase, the typical and "atypical", with a single member of the last group having been isolated to date, from Wolinella succinogenes. Thus, here the structure of the "typical" nitrous oxide reductase with either CuZ(4Cu2S) or CuZ∗(4Cu1S), as well as its spectroscopic and catalytic properties, will be discussed. © The Royal Society of Chemistry 2017.
Pauleta, S. R., A. Cooper, M. Nutley, N. Errington, S. Harding, F. Guerlesquin, C. F. Goodhew, I. Moura, JJG Moura, and G. W. Pettigrew. "
A copper protein and a cytochrome bind at the same site on bacterial cytochrome c peroxidase."
Biochemistry. 43 (2004): 14566-14576.
AbstractPseudoazurin binds at a single site on cytochrome c peroxidase from Paracoccus pantotrophus with a K-d of 16.4 muM at 25 degreesC, pH 6.0, in an endothermic reaction that is driven by a large entropy change. Sedimentation velocity experiments confirmed the presence of a single site, although results at higher pseudoazurin concentrations are complicated by the dimerization of the protein. Microcalorimetry, ultracentrifugation, and H-1 NMR spectroscopy studies in which cytochrome c550, pseudoazurin, and cytochrome c peroxidase were all present could be modeled using a competitive binding algorithm. Molecular docking simulation of the binding of pseudoazurin to the peroxidase in combination with the chemical shift perturbation pattern for pseudoazurin in the presence of the peroxidase revealed a group of solutions that were situated close to the electron-transferring heme with Cu-Fe distances of about 14 Angstrom. This is consistent with the results of H-1 NMR spectroscopy, which showed that pseudoazurin binds closely enough to the electron - transferring heme of the peroxidase to perturb its set of heme methyl resonances. We conclude that cytochrome c550 and pseudoazurin bind at the same site on the cytochrome c peroxidase and that the pair of electrons required to restore the enzyme to its active state after turnover are delivered one-by-one to the electron-transferring heme.