Cytochrome cbb3 oxidase and bacterial microaerobic metabolism

2002 ◽  
Vol 30 (4) ◽  
pp. 653-658 ◽  
Author(s):  
R. S. Pitcher ◽  
T. Brittain ◽  
N. J. Watmugh
Keyword(s):  
Active Site ◽  
Reduction Potential ◽  
Oxygen Affinity ◽  
Pseudomonas Stutzeri ◽  
Spectroscopic Characterization ◽  
High Oxygen Affinity ◽  
Copper Oxidase ◽  
Reduced State

Cytochrome cbb3 oxidase is a member of the haem-copper oxidase superfamily. It is characterized by its high oxygen affinity, while retaining the ability to pump protons. These attributes are central to its proposed role in bacterial microaerobic metabolism. Recent spectroscopic characterization of both the cytochrome cbb3 oxidase complex from Pseudomonas stutzeri and the dihaem ccoP subunit expressed separately in Escherichia coli has revealed the presence of a low-spin His/His co-ordinated c-type cytochrome. The low midpoint reduction potential of this haem (Em < + 100 mV), together with its unexpected ability to bind CO in the reduced state at the expense of the distal histidine ligand, raises questions about the role of the ccoP subunit in the delivery of electrons to the active site.

Characterization of anEscherichia coliSulfite Oxidase Homologue Reveals the Role of a Conserved Active Site Cysteine in Assembly and Function†

Biochemistry ◽  
2005 ◽  
Vol 44 (30) ◽  
pp. 10339-10348 ◽  
Author(s):  
Stephen J. Brokx ◽  
Richard A. Rothery ◽  
Guijin Zhang ◽  
Derek P. Ng ◽  
Joel H. Weiner
Keyword(s):  
Active Site ◽  
Active Site Cysteine ◽  
And Function

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

2007 ◽  
Vol 20 (10) ◽  
pp. 1241-1249 ◽  
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.

Spectroscopic characterization of free-base hydroxy(arylethynyl)porphyrins in acidic and basic media

2017 ◽  
Vol 21 (10) ◽  
pp. 680-691
Author(s):  
Kaarin K. Evens ◽  
Kathryn E. Splan
Keyword(s):  
Spectroscopic Characterization ◽  
Spectral Features ◽  
Free Base ◽  
Enhanced Absorption ◽  
Spectral Shifts ◽  
Porphyrin Macrocycle ◽  
Show Evidence ◽  
Acidic Conditions

The addition of arylethynyl groups to the porphyrin macrocycle represents an effective strategy with which to enhance the light-harvesting properties of porphyrins. We now extend this modification to arylethynyl porphyrins with two or four [Formula: see text]-hydroxyphenyl substituents. Arylethynyl porphyrins bearing four, but not two, [Formula: see text]-hydroxyphenyl substituents show evidence of aggregation under acidic conditions. Under basic conditions, deprotonation of the peripheral hydroxyphenyl substituents results in substantially red-shifted spectral features and enhanced absorption in the Q-band region. When the hydroxyphenyl groups are appended to the porphyrin macrocylce via the ethynyl spacers, the spectral shifts observed upon deprotonation are significantly enhanced relative to those observed for hydroxyphenylporphyrins, highlighting the role of expanded conjugation in altering porphyrin photophysics.

Hemoglobin Dallas (α97(G4)Asn→Lys):functional characterization of a high oxygen affinity natural mutant

1992 ◽  
Vol 1180 (1) ◽  
pp. 15-20 ◽  
Author(s):  
E. Lendaro ◽  
R. Ippoliti ◽  
A. Brancaccio ◽  
A. Bellelli ◽  
B. Vallone ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Oxygen Affinity ◽  
High Oxygen ◽  
High Oxygen Affinity

scholarly journals Structural and Spectroscopic Characterization of TPGS Micelles: Disruptive Role of Cyclodextrins and Kinetic Pathways

Langmuir ◽  
2017 ◽  
Vol 33 (19) ◽  
pp. 4737-4747 ◽  
Author(s):  
Joan Puig-Rigall ◽  
Isabelle Grillo ◽  
Cécile A. Dreiss ◽  
Gustavo González-Gaitano
Keyword(s):  
Spectroscopic Characterization

scholarly journals FMN-dependent oligomerization of putative lactate oxidase from Pediococcus acidilactici

2019 ◽  
Author(s):  
Yashwanth Ashok ◽  
Mirko M. Maksimainen ◽  
Tuija Kallio ◽  
Pekka Kilpeläinen ◽  
Lari Lehtiö
Keyword(s):  
Hydrogen Peroxide ◽  
Active Site ◽  
Pediococcus Acidilactici ◽  
Active Site Residues ◽  
Lactate Oxidase ◽  
Monooxygenase Activity ◽  
Aerococcus Viridans ◽  
Lactate Levels

AbstractLactate oxidases belong to a group of FMN-dependent enzymes and they catalyze a conversion of lactate to pyruvate with a release of hydrogen peroxide. Hydrogen peroxide is also utilized as a read out in biosensors to quantitate lactate levels in biological samples. Aerococcus viridans lactate oxidase is the best characterized lactate oxidase and our knowledge of lactate oxidases relies largely to studies conducted with that particular enzyme. Pediococcus acidilactici lactate oxidase is also commercially available for e.g. lactate measurements, but this enzyme has not been characterized before in detail. Here we report structural characterization of the recombinant enzyme and its co-factor dependent oligomerization. The crystal structures revealed two distinct conformations in the loop closing the active site, consistent with previous biochemical studies implicating the role of loop in catalysis. Despite the structural conservation of active site residues when compared to Aerococcus viridans lactate oxidase we were not able to detect either oxidase or monooxygenase activity when L-lactate or other potential alpha hydroxyl acids were used as a substrate. Pediococcus acidilactici lactate oxidase is therefore an example of a misannotation of an FMN-dependent enzyme, which catalyzes likely a so far unknown oxidation reaction.

scholarly journals Structural Characterization of an S-enantioselective Imine Reductase from Mycobacterium Smegmatis

Biomolecules ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1130
Author(s):  
Timo Meyer ◽  
Nadine Zumbrägel ◽  
Christina Geerds ◽  
Harald Gröger ◽  
Hartmut H. Niemann
Keyword(s):  
Substrate Specificity ◽  
Active Site ◽  
Mycobacterium Smegmatis ◽  
Catalytic Mechanism ◽  
Building Blocks ◽  
Secondary Amines ◽  
Hydrophobic Amino Acids ◽  
High Degree

NADPH-dependent imine reductases (IREDs) are enzymes capable of enantioselectively reducing imines to chiral secondary amines, which represent important building blocks in the chemical and pharmaceutical industry. Since their discovery in 2011, many previously unknown IREDs have been identified, biochemically and structurally characterized and categorized into families. However, the catalytic mechanism and guiding principles for substrate specificity and stereoselectivity remain disputed. Herein, we describe the crystal structure of S-IRED-Ms from Mycobacterium smegmatis together with its cofactor NADPH. S-IRED-Ms belongs to the S-enantioselective superfamily 3 (SFam3) and is the first IRED from SFam3 to be structurally described. The data presented provide further evidence for the overall high degree of structural conservation between different IREDs of various superfamilies. We discuss the role of Asp170 in catalysis and the importance of hydrophobic amino acids in the active site for stereospecificity. Moreover, a separate entrance to the active site, potentially functioning according to a gatekeeping mechanism regulating access and, therefore, substrate specificity is described.

scholarly journals Carbon dioxide binding at a Ni/Fe center: synthesis and characterization of Ni(η1-CO2-κC) and Ni-μ-CO2-κC:κ2O,O′-Fe

2017 ◽  
Vol 8 (1) ◽  
pp. 600-605 ◽  
Author(s):  
Changho Yoo ◽  
Yunho Lee
Keyword(s):  
Carbon Dioxide ◽  
Active Site ◽  
Synthesis And Characterization ◽  
Fe Species

A heterobimetallic Ni-μ-CO2-κC:κ2O,O′-Fe species reminiscent of the CODH active site was synthesized, helping to elucidate the role of the unique iron.

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