Partial and complete denitrification in Thermus thermophilus: lessons from genome drafts

2011 ◽  
Vol 39 (1) ◽  
pp. 249-253 ◽  
Author(s):  
Carlos Bricio ◽  
Laura Alvarez ◽  
Manuel J. Gómez ◽  
José Berenguer
Keyword(s):  
Nitric Oxide ◽  
Cytochrome C ◽  
Nitrate Reductase ◽  
Nitrogen Balance ◽  
Nitrite Reductase ◽  
Thermus Thermophilus ◽  
Variable Region ◽  
Nitric Oxide Reductase ◽  
Genes Encoding ◽  
Cytochrome Cd1

We have obtained draft genomic sequences of PD (partial denitrificant) and CD (complete denitrificant) strains of Thermus thermophilus. Their genomes are similar in size to that of the aerobic strains sequenced to date and probably contain a similar megaplasmid. In the CD strain, the genes encoding a putative cytochrome cd1 Nir (nitrite reductase) and ancillary proteins were clustered with a cytochrome c-dependent Nor (nitric oxide reductase), and with genes that are probably implicated in their regulation. The Nar (nitrate reductase) and associated genes were also clustered and located 7 kb downstream of the genes coding for the Nir. The whole nar–nir–nor denitrification supercluster was identified as part of a variable region of a megaplasmid. No homologues of NosZ were found despite nitrogen balance supports the idea that such activity actually exists.

New insights into the activity of Pseudomonas aeruginosa cd1 nitrite reductase

2008 ◽  
Vol 36 (6) ◽  
pp. 1155-1159 ◽  
Author(s):  
Serena Rinaldo ◽  
Alessandro Arcovito ◽  
Giorgio Giardina ◽  
Nicoletta Castiglione ◽  
Maurizio Brunori ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pseudomonas Aeruginosa ◽  
Nitrite Reductase ◽  
Nitrite Reduction ◽  
Nitrite Reductases ◽  
Cytochrome Cd1 ◽  
Haem Iron ◽  
Shed Light ◽  
Denitrification Process

The cytochrome cd1 nitrite reductases are enzymes that catalyse the reduction of nitrite to nitric oxide (NO) in the bacterial energy conversion denitrification process. These enzymes contain two different redox centres: one covalently bound c-haem, which is reduced by external donors, and one peculiar d1-haem, where catalysis occurs. In the present paper, we summarize the current understanding of the reaction of nitrite reduction in the light of the most recent results on the enzyme from Pseudomonas aeruginosa and discuss the differences between enzymes from different organisms. We have evidence that release of NO from the ferrous d1-haem occurs rapidly enough to be fully compatible with the turnover, in contrast with previous hypotheses, and that the substrate nitrite is able to displace NO from the d1-haem iron. These results shed light on the mechanistic details of the activity of cd1 nitrite reductases and on the biological role of the d1-haem, whose presence in this class of enzymes has to date been unexplained.

scholarly journals Functional interactions between nitrite reductase and nitric oxide reductase from Paracoccus denitrificans

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ingrid Albertsson ◽  
Johannes Sjöholm ◽  
Josy ter Beek ◽  
Nicholas J. Watmough ◽  
Jerker Widengren ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrite Reductase ◽  
Paracoccus Denitrificans ◽  
Affinity Constant ◽  
Nitric Oxide Reductase ◽  
Terminal Electron Acceptor ◽  
Model Soil ◽  
Transient Interactions ◽  
Electron Donation

AbstractDenitrification is a microbial pathway that constitutes an important part of the nitrogen cycle on earth. Denitrifying organisms use nitrate as a terminal electron acceptor and reduce it stepwise to nitrogen gas, a process that produces the toxic nitric oxide (NO) molecule as an intermediate. In this work, we have investigated the possible functional interaction between the enzyme that produces NO; the cd1 nitrite reductase (cd1NiR) and the enzyme that reduces NO; the c-type nitric oxide reductase (cNOR), from the model soil bacterium P. denitrificans. Such an interaction was observed previously between purified components from P. aeruginosa and could help channeling the NO (directly from the site of formation to the side of reduction), in order to protect the cell from this toxic intermediate. We find that electron donation to cNOR is inhibited in the presence of cd1NiR, presumably because cd1NiR binds cNOR at the same location as the electron donor. We further find that the presence of cNOR influences the dimerization of cd1NiR. Overall, although we find no evidence for a high-affinity, constant interaction between the two enzymes, our data supports transient interactions between cd1NiR and cNOR that influence enzymatic properties of cNOR and oligomerization properties of cd1NiR. We speculate that this could be of particular importance in vivo during metabolic switches between aerobic and denitrifying conditions.

scholarly journals Novel nitrite reductase domain structure suggests a chimeric denitrification repertoire in Phylum Chloroflexi

2021 ◽  
Author(s):  
Sarah Schwartz ◽  
Lily Momper ◽  
L. Thiberio Rangel ◽  
Cara Magnabosco ◽  
Jan Amend ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrite Reductase ◽  
Phylogenetic Analyses ◽  
Domain Architecture ◽  
Terrestrial Ecosystems ◽  
Genomic Diversity ◽  
Nitric Oxide Reductase ◽  
Fusion Event ◽  
Ecological Carrying Capacity ◽  
Global Nitrogen Cycle

Denitrification plays a central role in the global nitrogen cycle, reducing and removing nitrogen from marine and terrestrial ecosystems. The flux of nitrogen species through this pathway has a widespread impact, affecting ecological carrying capacity, agriculture, and climate. Nitrite reductase (Nir) and nitric oxide reductase (NOR) are the two central enzymes in this pathway. Here we present a previously unreported Nir domain architecture in members of Phylum Chloroflexi. Phylogenetic analyses of protein domains within Nir indicate that an ancestral horizontal transfer and fusion event produced this chimeric domain architecture. We also identify an expanded genomic diversity of a rarely reported nitric oxide reductase subtype, eNOR. Together, these results suggest a greater diversity of denitrification enzyme arrangements exist than have been previously reported.

scholarly journals Investigation of cytochrome c dependent nitric oxide reductase (cNOR) from Paracoccus denitrificans

2016 ◽  
Vol 1857 ◽  
pp. e91
Author(s):  
Sinan Sabuncu ◽  
Josy Ter Beek ◽  
Madeleine Strickland ◽  
Pia Ädelroth ◽  
Frederic Melin ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cytochrome C ◽  
Paracoccus Denitrificans ◽  
Nitric Oxide Reductase
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