ATP Binding to Nitrogenase and ATP-Driven Electron Transfer in Nitrogen Fixation

1992 ◽  
pp. 119-150
Author(s):  
Chong-Biao You ◽  
Wei Song ◽  
Ding Zeng ◽  
K. R. Tsai
Keyword(s):  
Electron Transfer ◽  
Nitrogen Fixation ◽  
Atp Binding

scholarly journals Spectroscopic, thermodynamic and computational evidence of the locations of the FADs in the nitrogen fixation-associated electron transfer flavoprotein

2019 ◽  
Vol 10 (33) ◽  
pp. 7762-7772 ◽  
Author(s):  
Nishya Mohamed-Raseek ◽  
H. Diessel Duan ◽  
Peter Hildebrandt ◽  
Maria Andrea Mroginski ◽  
Anne-Frances Miller
Keyword(s):  
Electron Transfer ◽  
Nitrogen Fixation ◽  
Electron Transfer Flavoprotein

Experiments and computation establish the locations of the two flavins whose contrasting reactivities produce electron bifurcation in ETFs. They confirm the accepted model and support homologies & distinctions between bifurcating and canonical ETFs.

scholarly journals Redundancy in Periplasmic Binding Protein-Dependent Transport Systems for Trehalose, Sucrose, and Maltose in Sinorhizobium meliloti

2002 ◽  
Vol 184 (11) ◽  
pp. 2978-2986 ◽  
Author(s):  
John Beck Jensen ◽  
N. Kent Peters ◽  
T. V. Bhuvaneswari
Keyword(s):  
Nitrogen Fixation ◽  
Sinorhizobium Meliloti ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Gene Replacement ◽  
Transport Systems ◽  
Atp Binding ◽  
Dependent Transport ◽  
Atp Binding Protein ◽  
Growth Experiments

ABSTRACT We have identified a cluster of six genes involved in trehalose transport and utilization (thu) in Sinorhizobium meliloti. Four of these genes, thuE, -F, -G, and -K, were found to encode components of a binding protein-dependent trehalose/maltose/sucrose ABC transporter. Their deduced gene products comprise a trehalose/maltose-binding protein (ThuE), two integral membrane proteins (ThuF and ThuG), and an ATP-binding protein (ThuK). In addition, a putative regulatory protein (ThuR) was found divergently transcribed from the thuEFGK operon. When the thuE locus was inactivated by gene replacement, the resulting S. meliloti strain was impaired in its ability to grow on trehalose, and a significant retardation in growth was seen on maltose as well. The wild type and the thuE mutant were indistinguishable for growth on glucose and sucrose. This suggested a possible overlap in function of the thuEFGK operon with the aglEFGAK operon, which was identified as a binding protein-dependent ATP-binding transport system for sucrose, maltose, and trehalose. The Km s for trehalose transport were 8 ± 1 nM and 55 ± 5 nM in the uninduced and induced cultures, respectively. Transport and growth experiments using mutants impaired in either or both of these transport systems show that these systems form the major transport systems for trehalose, maltose, and sucrose. By using a thuE′-lacZ fusion, we show that thuE is induced only by trehalose and not by cellobiose, glucose, maltopentaose, maltose, mannitol, or sucrose, suggesting that the thuEFGK system is primarily targeted toward trehalose. The aglEFGAK operon, on the other hand, is induced primarily by sucrose and to a lesser extent by trehalose. Tests for root colonization, nodulation, and nitrogen fixation suggest that uptake of disaccharides can be critical for colonization of alfalfa roots but is not important for nodulation and nitrogen fixation per se.

scholarly journals The flexible N-terminus of BchL protects its [4Fe-4S] cluster in oxygenic environments and autoinhibits activity

2019 ◽  
Author(s):  
Elliot Corless ◽  
Syed Muhammad Saad Imran ◽  
Maxwell B. Watkins ◽  
Sofia Origanti ◽  
John-Paul Bacik ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Enzyme Stability ◽  
Binding Pocket ◽  
Free Form ◽  
Release Mechanism ◽  
Atp Binding ◽  
Atp Binding Site ◽  
Substrate Reduction ◽  
Evolutionarily Conserved ◽  
N Terminus

AbstractThe dark-operative protochlorophyllide oxidoreductase (DPOR) enzyme contains two [4Fe-4S]- containing component proteins (BchL and BchNB) that assemble in an ATP-dependent fashion to coordinate electron transfer and reduction of protochlorophyllide to chlorophyllide. Photosynthesis generates an oxygenic environment that is non-optimal for [Fe-S] clusters and we here present an elegant evolutionarily conserved mechanism in BchL to protect its [4Fe-4S] cluster. We present a crystal structure of BchL in the nucleotide-free form with an ordered N-terminus that shields the [4Fe-4S] cluster at the docking interface between BchL and BchNB. Amino acid substitutions that perturb the shielding of the [4Fe-4S] cluster produce an unstable, but hyper-active enzyme complex, suggesting a role for the N-terminus in both auto-inhibition and enzyme stability. Upon ATP binding, a patch of amino acids, Asp-Phe-Asp (‘DFD patch’), situated at the mouth of the BchL ATP-binding pocket promotes inter-subunit cross stabilization of the two subunits and relieves the auto-inhibition by the N-terminus. A linked BchL dimer with one defective ATP-binding site does not support substrate reduction, illustrating that nucleotide binding to both subunits is a prerequisite for the inter-subunit cross stabilization. We propose that ATP-binding produces a conformational compaction of the BchL homodimer leading to a release of the flexible N-terminus from blocking the [4Fe-4S] cluster and promotes complex formation with BchNB to drive electron transfer. The auto-inhibitive feature and release mechanism appear unique to DPOR and is not found in the structurally similar nitrogenase.

scholarly journals Electron Transfer to Nitrogenase in Different Genomic and Metabolic Backgrounds

2018 ◽  
Vol 200 (10) ◽  
Author(s):  
Saroj Poudel ◽  
Daniel R. Colman ◽  
Kathryn R. Fixen ◽  
Rhesa N. Ledbetter ◽  
Yanning Zheng ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Nitrogen Fixation ◽  
Energy Metabolism ◽  
Host Cells ◽  
Content Type ◽  
Anoxygenic Phototrophs ◽  
Facultatively Anaerobic ◽  
Facultative Anaerobes ◽  
Ion Translocation ◽  
Key Enzyme

ABSTRACTNitrogenase catalyzes the reduction of dinitrogen (N2) using low-potential electrons from ferredoxin (Fd) or flavodoxin (Fld) through an ATP-dependent process. Since its emergence in an anaerobic chemoautotroph, this oxygen (O2)-sensitive enzyme complex has evolved to operate in a variety of genomic and metabolic backgrounds, including those of aerobes, anaerobes, chemotrophs, and phototrophs. However, whether pathways of electron delivery to nitrogenase are influenced by these different metabolic backgrounds is not well understood. Here, we report the distribution of homologs of Fds, Flds, and Fd-/Fld-reducing enzymes in 359 genomes of putative N2fixers (diazotrophs). Six distinct lineages of nitrogenase were identified, and their distributions largely corresponded to differences in the host cells' ability to integrate O2or light into energy metabolism. The predicted pathways of electron transfer to nitrogenase in aerobes, facultative anaerobes, and phototrophs varied from those in anaerobes at the levels of Fds/Flds used to reduce nitrogenase, the enzymes that generate reduced Fds/Flds, and the putative substrates of these enzymes. Proteins that putatively reduce Fd with hydrogen or pyruvate were enriched in anaerobes, while those that reduce Fd with NADH/NADPH were enriched in aerobes, facultative anaerobes, and anoxygenic phototrophs. The energy metabolism of aerobic, facultatively anaerobic, and anoxygenic phototrophic diazotrophs often yields reduced NADH/NADPH that is not sufficiently reduced to drive N2reduction. At least two mechanisms have been acquired by these taxa to overcome this limitation and to generate electrons with potentials capable of reducing Fd. These include the bifurcation of electrons or the coupling of Fd reduction to reverse ion translocation.IMPORTANCENitrogen fixation supplies fixed nitrogen to cells from a variety of genomic and metabolic backgrounds, including those of aerobes, facultative anaerobes, chemotrophs, and phototrophs. Here, using informatics approaches applied to genomic data, we show that pathways of electron transfer to nitrogenase in metabolically diverse diazotrophic taxa have diversified primarily in response to host cells' acquired ability to integrate O2or light into their energy metabolism. The acquisition of two key enzyme complexes enabled aerobic and facultatively anaerobic phototrophic taxa to generate electrons of sufficiently low potential to reduce nitrogenase: the bifurcation of electrons via the Fix complex or the coupling of Fd reduction to reverse ion translocation via theRhodobacternitrogen fixation (Rnf) complex.

ATP Binding and Aspartate Protonation Enhance Photoinduced Electron Transfer in Plant Cryptochrome

2014 ◽  
Vol 136 (37) ◽  
pp. 12974-12986 ◽  
Author(s):  
Fabien Cailliez ◽  
Pavel Müller ◽  
Michaël Gallois ◽  
Aurélien de la Lande
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Atp Binding

Engineering Cyanobacterium with Transmembrane Electron Transfer Ability for Bioelectrochemical Nitrogen Fixation

ACS Catalysis ◽  
2021 ◽  
pp. 13169-13179
Author(s):  
Fangyuan Dong ◽  
Yoo Seok Lee ◽  
Erin M. Gaffney ◽  
Willisa Liou ◽  
Shelley D. Minteer
Keyword(s):  
Electron Transfer ◽  
Nitrogen Fixation

Electron transfer in inorganic nitrogen fixation

1991 ◽  
Vol 30 (5) ◽  
pp. 882-883 ◽  
Author(s):  
T. Adrian. George ◽  
Bharat B. Kaul
Keyword(s):  
Electron Transfer ◽  
Nitrogen Fixation ◽  
Inorganic Nitrogen

scholarly journals Role for draTG and rnf Genes in Reduction of 2,4-Dinitrophenol by Rhodobacter capsulatus

2001 ◽  
Vol 183 (5) ◽  
pp. 1780-1783 ◽  
Author(s):  
Lara P. Sáez ◽  
Patricia Garcı́a ◽  
Manuel Martı́nez-Luque ◽  
Werner Klipp ◽  
Rafael Blasco ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Nitrogen Fixation ◽  
Deletion Mutant ◽  
Rhodobacter Capsulatus ◽  
Short Term ◽  
Phototrophic Bacterium ◽  
Reduction System ◽  
Nitroreductase Activity

ABSTRACT The phototrophic bacterium Rhodobacter capsulatus is able to reduce 2,4-dinitrophenol (DNP) to 2-amino-4-nitrophenol enzymatically and thus can grow in the presence of this uncoupler. DNP reduction was switched off by glutamine or ammonium, but this short-term regulation did not take place in a draTGdeletion mutant. Nevertheless, the target of DraTG does not seem to be the nitrophenol reductase itself since the ammonium shock did not inactivate the enzyme. In addition to this short-term regulation, ammonium or glutamine repressed the DNP reduction system. Mutants ofR. capsulatus affected in ntrC orrpoN exhibited a 10-fold decrease in nitroreductase activity in vitro but almost no DNP activity in vivo. In addition, mutants affected in rnfA or rnfC, which are also under NtrC control and encode components involved in electron transfer to nitrogenase, were unable to metabolize DNP. These results indicate that NtrC regulates dinitrophenol reduction in R. capsulatus, either directly or indirectly, by controlling expression of the Rnf proteins. Therefore, the Rnf complex seems to supply electrons for both nitrogen fixation and DNP reduction.

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