scholarly journals Roles of cytochromes c and b5 in mitochondria and microsomes: Classical and murburn perspectives

2020 ◽  
Author(s):  
Kelath Murali Manoj ◽  
Daniel Andrew Gideon
Keyword(s):  
Protein Interactions ◽  
Cytochrome B5 ◽  
Specific Interaction ◽  
Complex Iii ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Redox Equilibrium ◽  
Redox Partners ◽  
Cyt C ◽  
Altered Surface

While cytochrome c (Cyt. c) is a soluble protein involved in mitochondrial electron transfer (ET) reactions between Complex III and Complex IV, cytochrome b5 (Cyt. b5) is a microsomal membrane protein acting as a redox aide for diverse cytochrome P450s and their unique reductase. We found little conservation in the sequence and surface amino acid residues of Cyt. c and b5 proteins among evolutionarily diverse species. Hence, the logic that these proteins mediate ET through affinity binding via specific surface residues is weak. Also, analysis of putative protein-protein interactions in the crystal structures of these proteins and their redox partners did not point to any specific interaction logic. The literature on kinetic and thermodynamic constants of mutants (with altered surface residues) did not provide strong evidence to support the binding-based ET paradigm. Topographically divergent Cyt. b5 from one species has been shown to enhance the activity of CYP450 from another species, implying the involvement of non-specific interactions. These observations downplay the classical protein-protein biding based long range ET mechanism. Further, we provide evidence to show that murburn concept presents better chemico-physical logic for ETs mediated by Cyt. c and b5. To explain for the promiscuity of interactions, we conclude that the two proteins act as non-specific/generic redox capacitors, mediating a one-electron redox equilibrium involving diffusible reactive oxygen species (DROS) and ions.

scholarly journals Protein-protein interactions of cytochromes P450 3A4 and 3A5 with their intermediate redox partners cytochromes b5

2015 ◽  
Vol 61 (4) ◽  
pp. 468-474
Author(s):  
O.V. Gnedenko ◽  
A.S. Ivanov ◽  
E.O. Yablokov ◽  
S.A. Usanov ◽  
D.V. Mukha ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Dissociation Constants ◽  
Cytochromes P450 ◽  
Cytochrome B5 ◽  
Electrochemical Analysis ◽  
Monooxygenase System ◽  
Protein Protein Interactions ◽  
Reduction Potentials ◽  
Drug Biotransformation ◽  
Redox Partners

Molecular interactions between proteins redox partners (cytochromes Р450 3А4, 3А5 and cytochrome b5) within the monooxygenase system, which is known to be involved in drug biotransformation, were investigated. Human cytochromes Р450 3A4 and 3А5 (CYP3A4 and CYP3A5) form complexes with various cytochromes b5: the microsomal (b5mc) and mitochondrial (b5om) forms of this protein, as well as with 2 “chimeric” proteins, b5(om-mc), b5(mc-om). Kinetic constants and equilibrium dissociation constants were determined by the SPR biosensor. Essential distinction between CYP3A4 and CYP3A5 was only observed upon their interactions with cytochrome b5om. Electroanalytical characteristics of electrodes with immobilized hemoproteins were obtained. The electrochemical analysis of CYP3A4, CYP3A5, b5mc, b5om, b5(om-mc), and b5(mc-om) immobilized on screen printed graphite electrodes modified with membranous matrix revealed that these proteins have very close reduction potentials -0.435  -0.350 V (vs. Ag/AgCl). Cytochrome b5mc was shown to be capable of stimulating the electrocatalytic activity of CYP3A4 in the presence of its substrate testosterone.

scholarly journals Group I Metabotropic Glutamate Receptors and Interacting Partners: An Update

2022 ◽  
Vol 23 (2) ◽  
pp. 840
Author(s):  
Li-Min Mao ◽  
Alaya Bodepudi ◽  
Xiang-Ping Chu ◽  
John Q. Wang
Keyword(s):  
Synaptic Plasticity ◽  
Protein Interactions ◽  
Metabotropic Glutamate Receptors ◽  
Adaptor Proteins ◽  
Mammalian Brain ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Associated Proteins

Group I metabotropic glutamate (mGlu) receptors (mGlu1/5 subtypes) are G protein-coupled receptors and are broadly expressed in the mammalian brain. These receptors play key roles in the modulation of normal glutamatergic transmission and synaptic plasticity, and abnormal mGlu1/5 signaling is linked to the pathogenesis and symptomatology of various mental and neurological disorders. Group I mGlu receptors are noticeably regulated via a mechanism involving dynamic protein–protein interactions. Several synaptic protein kinases were recently found to directly bind to the intracellular domains of mGlu1/5 receptors and phosphorylate the receptors at distinct amino acid residues. A variety of scaffolding and adaptor proteins also interact with mGlu1/5. Constitutive or activity-dependent interactions between mGlu1/5 and their interacting partners modulate trafficking, anchoring, and expression of the receptors. The mGlu1/5-associated proteins also finetune the efficacy of mGlu1/5 postreceptor signaling and mGlu1/5-mediated synaptic plasticity. This review analyzes the data from recent studies and provides an update on the biochemical and physiological properties of a set of proteins or molecules that interact with and thus regulate mGlu1/5 receptors.

scholarly journals Characterization of COMMD protein–protein interactions in NF-κB signalling

2006 ◽  
Vol 398 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Prim de Bie ◽  
Bart van de Sluis ◽  
Ezra Burstein ◽  
Karen J. Duran ◽  
Ruud Berger ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Copper Metabolism ◽  
Nuclear Factor Κb ◽  
Inhibitory Effect ◽  
Protein Family ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Necrosis Factor

COMMD [copper metabolism gene MURR1 (mouse U2af1-rs1 region 1) domain] proteins constitute a recently identified family of NF-κB (nuclear factor κB)-inhibiting proteins, characterized by the presence of the COMM domain. In the present paper, we report detailed investigation of the role of this protein family, and specifically the role of the COMM domain, in NF-κB signalling through characterization of protein–protein interactions involving COMMD proteins. The small ubiquitously expressed COMMD6 consists primarily of the COMM domain. Therefore COMMD1 and COMMD6 were analysed further as prototype members of the COMMD protein family. Using specific antisera, interaction between endogenous COMMD1 and COMMD6 is described. This interaction was verified by independent techniques, appeared to be direct and could be detected throughout the whole cell, including the nucleus. Both proteins inhibit TNF (tumour necrosis factor)-induced NF-κB activation in a non-synergistic manner. Mutation of the amino acid residues Trp24 and Pro41 in the COMM domain of COMMD6 completely abolished the inhibitory effect of COMMD6 on TNF-induced NF-κB activation, but this was not accompanied by loss of interaction with COMMD1, COMMD6 or the NF-κB subunit RelA. In contrast with COMMD1, COMMD6 does not bind to IκBα (inhibitory κBα), indicating that both proteins inhibit NF-κB in an overlapping, but not completely similar, manner. Taken together, these data support the significance of COMMD protein–protein interactions and provide new mechanistic insight into the function of this protein family in NF-κB signalling.

scholarly journals Mitochondria: Regulators of Cell Death and Survival

2002 ◽  
Vol 2 ◽  
pp. 1569-1578 ◽  
Author(s):  
David J. Granville ◽  
Roberta A. Gottlieb
Keyword(s):  
Cell Death ◽  
Conformational Changes ◽  
Protein Interactions ◽  
Apoptotic Cell ◽  
Critical Role ◽  
Death Process ◽  
Protein Protein Interactions ◽  
Ionic Changes ◽  
A Cell ◽  
Cyt C

The past 5 years has seen an intense surge in research devoted toward understanding the critical role of mitochondria in the regulation of cell death. Apoptosis can be initiated by a wide array of stimuli, inducing multiple signaling pathways that, for the most part, converge at the mitochondrion. Although classically considered the powerhouses of the cell, it is now understood that mitochondria are also “gatekeepers” that ultimately determine the fate of the cell. The mitochondrial decision as to whether a cell lives or dies is complex, involving protein-protein interactions, ionic changes, reactive oxygen species, and other mechanisms that require further elucidation. Once the death process is initiated, mitochondria undergo conformational changes, resulting in the release of cytochrome c (cyt c), caspases, endonucleases, and other factors leading to the onset and execution of apoptosis. The present review attempts to outline the complex milieu of events regulating the mitochondrial commitment to and processes involved in the implementation of the executioner phase of apoptotic cell death.

SPR Analysis of Protein-Protein Interactions Involving Cytochromes P450 and Cytochrome b5 Integrated into Lipid Membrane

2020 ◽  
Vol 14 (2) ◽  
pp. 168-173
Author(s):  
L. A. Kaluzhskiy ◽  
P. V. Ershov ◽  
K. S. Kurpedinov ◽  
D. S. Sonina ◽  
E. O. Yablokov ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Lipid Membrane ◽  
Cytochromes P450 ◽  
Cytochrome B5 ◽  
Protein Protein Interactions

scholarly journals The Effect of Proline cis-trans Isomerization on the Folding of the C-Terminal SH2 Domain from p85

2019 ◽  
Vol 21 (1) ◽  
pp. 125
Author(s):  
Francesca Troilo ◽  
Francesca Malagrinò ◽  
Lorenzo Visconti ◽  
Angelo Toto ◽  
Stefano Gianni
Keyword(s):  
Protein Interactions ◽  
Specific Interaction ◽  
Sh2 Domain ◽  
Regulatory Subunit ◽  
Wild Type ◽  
Protein Protein Interactions ◽  
Sh2 Domains ◽  
Trans Isomerization ◽  
A Site ◽  
Kinetics Of

SH2 domains are protein domains that modulate protein–protein interactions through a specific interaction with sequences containing phosphorylated tyrosines. In this work, we analyze the folding pathway of the C-terminal SH2 domain of the p85 regulatory subunit of the protein PI3K, which presents a proline residue in a cis configuration in the loop between the βE and βF strands. By employing single and double jump folding and unfolding experiments, we demonstrate the presence of an on-pathway intermediate that transiently accumulates during (un)folding. By comparing the kinetics of folding of the wild-type protein to that of a site-directed variant of C-SH2 in which the proline was replaced with an alanine, we demonstrate that this intermediate is dictated by the peptidyl prolyl cis-trans isomerization. The results are discussed in the light of previous work on the effect of peptidyl prolyl cis-trans isomerization on folding events.

scholarly journals A distinct class of plant and animal viral proteins that disrupt mitosis by directly interrupting the mitotic entry switch Wee1-Cdc25-Cdk1

2020 ◽  
Vol 6 (20) ◽  
pp. eaba3418
Author(s):  
Huaibing Jin ◽  
Zhiqiang Du ◽  
Yanjing Zhang ◽  
Judit Antal ◽  
Zongliang Xia ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Viral Proteins ◽  
Plant Viruses ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Common Amino Acid ◽  
Mitotic Entry ◽  
Distinct Class ◽  
Barley Yellow Dwarf ◽  
Hiv 1

Many animal viral proteins, e.g., Vpr of HIV-1, disrupt host mitosis by directly interrupting the mitotic entry switch Wee1-Cdc25-Cdk1. However, it is unknown whether plant viruses may use this mechanism in their pathogenesis. Here, we report that the 17K protein, encoded by barley yellow dwarf viruses and related poleroviruses, delays G2/M transition and disrupts mitosis in both host (barley) and nonhost (fission yeast, Arabidopsis thaliana, and tobacco) cells through interrupting the function of Wee1-Cdc25-CDKA/Cdc2 via direct protein-protein interactions and alteration of CDKA/Cdc2 phosphorylation. When ectopically expressed, 17K disrupts the mitosis of cultured human cells, and HIV-1 Vpr inhibits plant cell growth. Furthermore, 17K and Vpr share similar secondary structural feature and common amino acid residues required for interacting with plant CDKA. Thus, our work reveals a distinct class of mitosis regulators that are conserved between plant and animal viruses and play active roles in viral pathogenesis.

Analysis of an engineered plasma kallikrein inhibitor and its effect on contact activation

2010 ◽  
Vol 391 (4) ◽  
Author(s):  
A. Allart Stoop ◽  
Ravi V. Joshi ◽  
Christopher T. Eggers ◽  
Charles S. Craik
Keyword(s):  
Serine Protease ◽  
Protein Interactions ◽  
Phage Library ◽  
Plasma Kallikrein ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Contact Activation ◽  
Kallikrein Inhibitor ◽  
Membrane Type ◽  
Opposing Effects

AbstractEngineering of protein-protein interactions is used to enhance the affinity or specificity of proteins, such as antibodies or protease inhibitors, for their targets. However, fully diversifying all residues in a protein-protein interface is often unfeasible. Therefore, we limited our phage library for the serine protease inhibitor ecotin by restricting it to only tetranomial diversity and then targeted all 20 amino acid residues involved in protein recognition. This resulted in a high-affinity and highly specific plasma kallikrein inhibitor, ecotin-Pkal. To validate this approach we dissected the energetic contributions of each wild type (wt) or mutated surface loop to the binding of either plasma kallikrein (PKal) or membrane-type serine protease 1. The analysis demonstrated that a mutation in one loop has opposing effects depending on the sequence of surrounding loops. This finding stresses the cooperative nature of loop-loop interactions and justifies targeting multiple loops with a limited diversity. In contrast to ecotin wt, the specific loop combination of ecotin-Pkal discriminates the subtle structural differences between the active enzymes, PKal and Factor XIIa, and their respective zymogen forms. We used ecotin-Pkal to specifically inhibit contact activation of human plasma at the level mediated by plasma kallikrein.

Cardiac hypertrophy and altered β-adrenergic signaling in transgenic mice that express the amino terminus of β-ARK1

2003 ◽  
Vol 285 (5) ◽  
pp. H2201-H2211 ◽  
Author(s):  
Janelle R. Keys ◽  
Emily A. Greene ◽  
Chris J. Cooper ◽  
Sathyamangla V. Naga Prasad ◽  
Howard A. Rockman ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Cardiac Hypertrophy ◽  
Protein Interactions ◽  
Amino Terminus ◽  
Amino Acid Residues ◽  
Protein Protein Interactions ◽  
Gpcr Signaling ◽  
Amino Terminal ◽  
G Protein Coupled

The G protein-coupled receptor (GPCR) kinase β-adrenergic receptor (β-AR) kinase-1 (β-ARK1) is elevated during heart failure; however, its role is not fully understood. β-ARK1 contains several domains that are capable of protein-protein interactions that may play critical roles in the regulation of GPCR signaling. In this study, we developed a novel line of transgenic mice that express an amino-terminal peptide of β-ARK1 that is comprised of amino acid residues 50–145 (β-ARKnt) in the heart to determine whether this domain has any functional significance in vivo. Surprisingly, the β-ARKnt transgenic mice presented with cardiac hypertrophy. Our data suggest that the phenotype was driven via an enhanced β-AR system, as β-ARKnt mice had elevated cardiac β-AR density. Moreover, administration of a β-AR antagonist reversed hypertrophy in these mice. Interestingly, signaling through the β-AR in response to agonist stimulation was not enhanced in these mice. Thus the amino terminus of β-ARK1 appears to be critical for normal β-AR regulation in vivo, which further supports the hypothesis that β-ARK1 plays a key role in normal and compromised cardiac GPCR signaling.

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