The Klebsiella pneumoniae cytochrome bd' terminal oxidase complex and its role in microaerobic nitrogen fixation

Nitrogen fixation by aerobic prokaryotes appears paradoxical: the nitrogen-fixing enzymes—nitrogenases—are notoriously oxygen-labile, yet many bacteria fix nitrogen aerobically. This review summarises the evidence that cytochrome bd, a terminal oxidase unrelated to the mitochondrial and many other bacterial oxidases, plays a crucial role in aerotolerant nitrogen fixation in Azotobacter vinelandii and other bacteria by rapidly consuming oxygen during uncoupled respiration. We review the pertinent properties of this oxidase, particularly its complement of redox centres, the catalytic cycle of oxygen reduction, the affinity of the oxidase for oxygen, and the regulation of cytochrome bd gene expression. The roles of other oxidases and other mechanisms for limiting damage to nitrogenase are assessed.

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Effect of Membrane Environment on the Ligand-Binding Properties of the Terminal Oxidase Cytochrome bd-I from Escherichia coli

Biochemistry (Moscow) ◽

10.1134/s0006297920120123 ◽

2020 ◽

Vol 85 (12-13) ◽

pp. 1603-1612

Author(s):

V. B. Borisov

Keyword(s):

Escherichia Coli ◽

Ligand Binding ◽

Terminal Oxidase ◽

Binding Properties ◽

Cytochrome Bd

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Cardiolipin enhances the enzymatic activity of cytochrome bd and cytochrome bo3 solubilized in dodecyl-maltoside

Scientific Reports ◽

10.1038/s41598-021-87354-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Amer H. Asseri ◽

Albert Godoy-Hernandez ◽

Hojjat Ghasemi Goojani ◽

Holger Lill ◽

Junshi Sakamoto ◽

...

Keyword(s):

Escherichia Coli ◽

Oxygen Consumption ◽

Integral Membrane Proteins ◽

Terminal Oxidase ◽

Geobacillus Thermodenitrificans ◽

E Coli ◽

Cytochrome Bd ◽

Cytochrome Bo3 ◽

Dodecyl Maltoside ◽

Consumption Activity

AbstractCardiolipin (CL) is a lipid that is found in the membranes of bacteria and the inner membranes of mitochondria. CL can increase the activity of integral membrane proteins, in particular components of respiratory pathways. We here report that CL activated detergent-solubilized cytochrome bd, a terminal oxidase from Escherichia coli. CL enhanced the oxygen consumption activity ~ twofold and decreased the apparent KM value for ubiquinol-1 as substrate from 95 µM to 35 µM. Activation by CL was also observed for cytochrome bd from two Gram-positive species, Geobacillus thermodenitrificans and Corynebacterium glutamicum, and for cytochrome bo3 from E. coli. Taken together, CL can enhance the activity of detergent-solubilized cytochrome bd and cytochrome bo3.

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Nitrogen fixation by cell-free extracts of Klebsiella pneumoniae

Canadian Journal of Microbiology ◽

10.1139/m68-006 ◽

1968 ◽

Vol 14 (1) ◽

pp. 33-38 ◽

Cited By ~ 28

Author(s):

M. C. Mahl ◽

P. W. Wilson

Keyword(s):

Nitrogen Fixation ◽

Klebsiella Pneumoniae ◽

Azotobacter Vinelandii ◽

Ammonium Ion ◽

Michaelis Constant ◽

Nitrogen Gas ◽

Aerobacter Aerogenes ◽

Free System ◽

Evolving System ◽

A Cell

A cell-free system which permits nitrogen fixation by extracts of Klebsiella pneumoniae M5al (formerly Aerobacter aerogenes) has been developed. It is, essentially, that system described by Bulen and associates for Azotobacter vinelandii, utilizing ATP as a source of energy and dithionite as a source of electrons. The Michaelis constant for fixation has been estimated to be 0.12 atm. The extracts possessed an ATP-dependent hydrogen evolving system. Hydrogen evolution from these extracts was less under nitrogen than under helium in the presence of ATP. Nitrogen gas appears to be the inducer of nitrogen fixation. In the absence of N2, no induction of nitrogenase occurs. Nitrogenase is absent in cells grown on NH4+-N. There is a lag of about 13 h after the introduction of N2 gas into a culture which has depleted its supply of NH4+-N before nitrogenase can be detected. For reasons discussed in the text, this conclusion must be regarded as tentative at this time. Ammonium ion appears to prevent the synthesis of new molecules of nitrogenase without affecting the activity of those already formed.

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Nitrogen fixation (acetylene reduction) by Klebsiella pneumoniae in association with 'Park' Kentucky bluegrass (Poa pratensis L.)

Canadian Journal of Microbiology ◽

10.1139/m81-008 ◽

1981 ◽

Vol 27 (1) ◽

pp. 52-56 ◽

Cited By ~ 12

Author(s):

L. V. Wood ◽

R. V. Klucas ◽

R. C. Shearman

Keyword(s):

Nitrogen Fixation ◽

Klebsiella Pneumoniae ◽

Ethylene Production ◽

Acetylene Reduction ◽

Nitrogenase Activity ◽

Poa Pratensis ◽

Kentucky Bluegrass ◽

Surface Sterilization ◽

Reducing Activity ◽

Acetylene Reducing Activity

Turfs of 'Park' Kentucky bluegrass reestablished in the greenhouse and inoculated with Klebsiella pneumoniae (W6) showed significantly increased nitrogen fixation (acetylene reduction) compared with control turfs. Mean ethylene production rates per pot were 368 nmol h−1 for K. pneumoniae treated turfs, 55 nmol h−1 for heat-killed K. pneumoniae treated turfs, and 44 nmol h−1 for untreated turfs. Calculated lag periods before activity was observed were generally very short (less than 1 h).When 'Park' Kentucky bluegrass was grown from seed on soil-less medium of Turface, a fired aggregate clay, inoculation with K. pneumoniae (W6) resulted in 9 of 11 turfs showing nitrogenase activity (mean ethylene producion rate per pot was 195 nmol h−1). Only 3 of 11 turfs treated with heat-killed K. pneumoniae showed any activity and their mean rate of ethylene production (40 nmol h−1 per pot) was significantly lower than that for turfs treated with K. pneumoniae.Using the 'Park'–Turface soil-less model system it was shown that acetylene reducing activity was (i) root associated, (ii) generally highest at a depth of 1–4 cm below the surface, (iii) enhanced by washing excised roots, and (iv) inhibited by surface sterilization of excised roots. Klebsiella pneumoniae was recovered from Turface and roots showing acetylene reducing activity.

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Effect of Dimethyl Sulphoxide on the Expression of Nitrogen Fixation in Bacteria

Australian Journal of Biological Sciences ◽

10.1071/bi9770141 ◽

1977 ◽

Vol 30 (2) ◽

pp. 141 ◽

Cited By ~ 2

Author(s):

Mary L Skotnicki ◽

Barry G Rolfe

Keyword(s):

Escherichia Coli ◽

Nitrogen Fixation ◽

Energy Metabolism ◽

Membrane Proteins ◽

Klebsiella Pneumoniae ◽

Dimethyl Sulphoxide ◽

Rhizobium Trifolii ◽

Nif Genes ◽

E Coli ◽

Selection Of

Storage in dimethyl sulphoxide (DMSO) of Escherichia coli K12 hybrids carrying nif+ genes from Klebsiella pneumoniae can result in selection of a defective nitrogen-fixing phenotype. Similar results are obtained with E. coli K12 hybrids containing the nitrogep-fixing capacity from Rhizobium trifolii. DMSO appears to affect particular inner membrane proteins associated with energy metabolism in E. coli K12 and four chromosomal regions (chID, chlG, his and unc) are associated with resistance to DMSO.

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Novel Reiterated Fnr-Type Proteins Control the Production of the Symbiotic Terminal Oxidase cbb3 in Rhizobium etli CFN42

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-20-10-1241 ◽

2007 ◽

Vol 20 (10) ◽

pp. 1241-1249 ◽

Cited By ~ 15

Author(s):

Manuel J. Granados-Baeza ◽

Nicolás Gómez-Hernández ◽

Yolanda Mora ◽

María J. Delgado ◽

David Romero ◽

...

Keyword(s):

Nitrogen Fixation ◽

Oxygen Affinity ◽

Structural Similarity ◽

Transcriptional Regulators ◽

Terminal Oxidase ◽

Nitrogen Fixing ◽

Rhizobium Etli ◽

High Oxygen Affinity ◽

Key Genes

Symbiotic nitrogen-fixing bacteria express a terminal oxidase with a high oxygen affinity, the cbb3-type oxidase encoded by the fixNOQP operon. Previously, we have shown that, in Rhizobium etli CFN42, the repeated fixNOQP operons (fixNOQPd and fixNOQPf) have a differential role in nitrogen fixation. Only the fixNOQPd operon is required for the establishment of an effective symbiosis; microaerobic induction of this operon is under the control of at least three transcriptional regulators, FixKf, FnrNd, and FnrNchr, belonging to the Crp/Fnr family. In this work, we describe two novel Crp/Fnr-type transcriptional regulators (StoRd and StoRf, symbiotic terminal oxidase regulators) that play differential roles in the control of key genes for nitrogen fixation. Mutations either in stoRd or stoRf enhance the microaerobic expression of both fixNOQP reiterations, increasing also the synthesis of the cbb3-type oxidase in nodules. Despite their structural similarity, a differential role of these genes was also revealed, since a mutation in stoRd but not in stoRf enhanced both the expression of fixKf and the nitrogen-fixing capacity of R. etli CFN42.

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