scholarly journals Characterization of the nonheme iron center of cysteamine dioxygenase and its interaction with substrates

2020 ◽  
Vol 295 (33) ◽  
pp. 11789-11802
Author(s):  
Yifan Wang ◽  
Ian Davis ◽  
Yan Chan ◽  
Sunil G. Naik ◽  
Wendell P. Griffith ◽  
...  
Keyword(s):  
Sulfur Metabolism ◽  
Binding Mode ◽  
Nonheme Iron ◽  
Protein Signaling ◽  
Paramagnetic Resonance ◽  
Peptide Substrates ◽  
Oxygen Homeostasis ◽  
Physiological Processes ◽  
Dinitrosyl Iron ◽  
Iron Center

Cysteamine dioxygenase (ADO) has been reported to exhibit two distinct biological functions with a nonheme iron center. It catalyzes oxidation of both cysteamine in sulfur metabolism and N-terminal cysteine-containing proteins or peptides, such as regulator of G protein signaling 5 (RGS5). It thereby preserves oxygen homeostasis in a variety of physiological processes. However, little is known about its catalytic center and how it interacts with these two types of primary substrates in addition to O2. Here, using electron paramagnetic resonance (EPR), Mössbauer, and UV-visible spectroscopies, we explored the binding mode of cysteamine and RGS5 to human and mouse ADO proteins in their physiologically relevant ferrous form. This characterization revealed that in the presence of nitric oxide as a spin probe and oxygen surrogate, both the small molecule and the peptide substrates coordinate the iron center with their free thiols in a monodentate binding mode, in sharp contrast to binding behaviors observed in other thiol dioxygenases. We observed a substrate-bound B-type dinitrosyl iron center complex in ADO, suggesting the possibility of dioxygen binding to the iron ion in a side-on mode. Moreover, we observed substrate-mediated reduction of the iron center from ferric to the ferrous oxidation state. Subsequent MS analysis indicated corresponding disulfide formation of the substrates, suggesting that the presence of the substrate could reactivate ADO to defend against oxidative stress. The findings of this work contribute to the understanding of the substrate interaction in ADO and fill a gap in our knowledge of the substrate specificity of thiol dioxygenases.

scholarly journals Electron Paramagnetic Resonance Investigation of Nitrite Binding in Myoglobin

2018 ◽  
Author(s):  
Matthew Bawn ◽  
Fraser MacMillan
Keyword(s):  
Electron Paramagnetic Resonance ◽  
High Spin ◽  
Nitrite Reductase ◽  
Binding Mode ◽  
Nitrite Reduction ◽  
Paramagnetic Resonance ◽  
High Ph ◽  
Hypoxic Conditions ◽  
Electron Paramagnetic ◽  
Iron Center

ABSTRACTIt has been proposed that myoglobin (Mb) may act as a nitrite reductase under hypoxic conditions. Any mechanism describing such activity should take into account the binding geometry of the ligand to the heme. Crystal structures of horse-heart Mb and human hemoglobin-nitrite complexes suggest that the anion adopts an uncommon O-nitrito binding mode. Electron Paramagnetic Resonance (EPR) spectroscopy was employed to investigate the nature of nitrite binding to Mb at pH values ranging from 6.5 to 10.8. Results suggest that for ferric Mb at low pH, nitrite binds in the O-bound nitrito mode resulting in a low-spin (LS) iron center. Further a high-spin (HS) iron center is observed at high pH in Mb-Nitrite with spectral values different to that of purely HS-Mb that is proposed to be due to an N-bound nitrite. The yields of these two species were found to be influenced by pH.BackgroundMyoglobin has been theorized to have a role as a nitrite reductase.ResultsO-bound nitrite produces a low-spin ferric heme complex, whilst at high pH a high-spin species is found proposed to be the N-bound form.ConclusionNitrite may bind to heme in myoglobin via N-nitro or O-nitrito mode.SignificanceThe mechanism of any nitrite reduction will depend on its binding to the heme cofactor.

ДИНИТРОЗИЛЬНЫЕ КОМПЛЕКСЫ ЖЕЛЕЗА C ТИОЛСОДЕРЖАЩИМИ ЛИГАНДАМИ ПРЕДСТАВЛЕНЫ В ЖИВЫХ ОРГАНИЗМАХ В ОСНОВНОМ ИХ БИЯДЕРНОЙ ФОРМОЙ

2020 ◽  
Vol 65 (6) ◽  
pp. 1142-1153
Author(s):  
В.Д. Микоян ◽  
◽  
Е.Н. Бургова ◽  
Р.Р. Бородулин ◽  
А.Ф. Ванин ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Sodium Nitrite ◽  
Iron Complexes ◽  
Paramagnetic Resonance ◽  
First Case ◽  
Dinitrosyl Iron ◽  
Electron Paramagnetic ◽  
Dinitrosyl Complexes

The number of mononitrosyl iron complexes with diethyldithiocarbamate, formed in the liver of mice in vivo and in vitro after intraperitoneal injection of binuclear dinitrosyl iron complexes with N-acetyl-L-cysteine or glutathione, S-nitrosoglutathione, sodium nitrite or the vasodilating drug Isoket® was assessed by electron paramagnetic resonance (EPR). The number of the said complexes, in contrast to the complexes, formed after nitrite or Isoket administration, the level of which sharply increased after treatment of liver preparations with a strong reducing agent - dithionite, did not change in the presence of dithionite. It was concluded that, in the first case, EPR-detectable mononitrosyl iron complexes with diethyldithiocarbamate in the absence and presence of dithionite appeared as a result of the reaction of NO formed from nitrite with Fe2+-dieth- yldithiocarbamate and Fe3+-diethyldithiocarbamate complexes, respectively. In the second case, mononitrosyl iron complexes with diethyldithiocarbamate appeared as a result of the transition of iron-mononitosyl fragments from ready-made iron-dinitrosyl groups of binuclear dinitrosyl complexes, which is three to four times higher than the content of the mononuclear form of these complexes in the tissue...

Site of action of nonheme iron in the malate (flavine adenine dinucleotide) pathway of Mycobacterium phlei

1976 ◽  
Vol 22 (7) ◽  
pp. 1054-1057 ◽  
Author(s):  
A. K. Tyagi ◽  
T. L. Prasada Reddy ◽  
T. A. Venkitasubramanian
Keyword(s):  
Electron Transport ◽  
Ultraviolet Light ◽  
Nonheme Iron ◽  
Paramagnetic Resonance ◽  
Iron Protein ◽  
Mycobacterium Phlei ◽  
Diphenyl Tetrazolium Bromide ◽  
Electron Paramagnetic ◽  
Soluble Components ◽  
Malate Oxidation

Irradiation with ultraviolet light (360 nm) of cell-free extracts, electron-transport particles, and soluble components from Mycobacterium phlei resulted in the loss of malate oxidation by the flavine adenine dinucleotide pathway both in cell-free extracts and reconstituted systems. Addition of vitamin K1 restored the loss to the extent of 14% and 11% in cell-free extracts and reconstituted systems respectively. Electron-transport particles from M. phlei upon reduction with malate exhibited electron-paramagnetic resonance signals at g = 2.002 and 1.94, characteristic of napthosemiquinone and nonheme iron protein, respectively. Upon irradiating the particles with ultraviolet light (360 nm) these signals were not observed. Particulate flavine-adenine-dinucleotide-dependent malate dehydrogenase (EC 1.1.1.37) of M. phlei assayed by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide and phenazine methosulfate–2,6-dichlorophenolindophenol systems, which trap electrons at cytochrome c and at the flavine level respectively, was inhibited by o-phenanthroline. These observations suggest that nonheme iron protein is sensitive to ultraviolet light (360 nm) and participates before or in combination with flavine in the malate (flavine adenine dinucleotide) pathway of M. phlei.

scholarly journals An improved open-channel structure of MscL determined from FRET confocal microscopy and simulation

2010 ◽  
Vol 136 (4) ◽  
pp. 483-494 ◽  
Author(s):  
Ben Corry ◽  
Annette C. Hurst ◽  
Prithwish Pal ◽  
Takeshi Nomura ◽  
Paul Rigby ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Conformational Changes ◽  
Brownian Dynamics ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Channel Structure ◽  
Paramagnetic Resonance ◽  
Physiological Processes ◽  
Lipid Environment ◽  
Dynamics Simulations

Mechanosensitive channels act as molecular transducers of mechanical force exerted on the membrane of living cells by opening in response to membrane bilayer deformations occurring in physiological processes such as touch, hearing, blood pressure regulation, and osmoregulation. Here, we determine the likely structure of the open state of the mechanosensitive channel of large conductance using a combination of patch clamp, fluorescence resonance energy transfer (FRET) spectroscopy, data from previous electron paramagnetic resonance experiments, and molecular and Brownian dynamics simulations. We show that structural rearrangements of the protein can be measured in similar conditions as patch clamp recordings while controlling the state of the pore in its natural lipid environment by modifying the lateral pressure distribution via the lipid bilayer. Transition to the open state is less dramatic than previously proposed, while the N terminus remains anchored at the surface of the membrane where it can either guide the tilt of or directly translate membrane tension to the conformation of the pore-lining helix. Combining FRET data obtained in physiological conditions with simulations is likely to be of great value for studying conformational changes in a range of multimeric membrane proteins.

scholarly journals Introducing a 2-His-1-Glu Nonheme Iron Center into Myoglobin Confers Nitric Oxide Reductase Activity

2010 ◽  
Vol 132 (29) ◽  
pp. 9970-9972 ◽  
Author(s):  
Ying-Wu Lin ◽  
Natasha Yeung ◽  
Yi-Gui Gao ◽  
Kyle D. Miner ◽  
Lanyu Lei ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Reductase Activity ◽  
Nonheme Iron ◽  
Nitric Oxide Reductase ◽  
Iron Center

scholarly journals Mechanisms of adhesion G protein–coupled receptor activation

2020 ◽  
Vol 295 (41) ◽  
pp. 14065-14083 ◽  
Author(s):  
Alexander Vizurraga ◽  
Rashmi Adhikari ◽  
Jennifer Yeung ◽  
Maiya Yu ◽  
Gregory G. Tall
Keyword(s):  
G Protein ◽  
Receptor Activation ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Physiological Processes ◽  
Class B ◽  
Peptide Agonist ◽  
G Protein Coupled ◽  
Existing Structure

Adhesion G protein–coupled receptors (AGPCRs) are a thirty-three-member subfamily of Class B GPCRs that control a wide array of physiological processes and are implicated in disease. AGPCRs uniquely contain large, self-proteolyzing extracellular regions that range from hundreds to thousands of residues in length. AGPCR autoproteolysis occurs within the extracellular GPCR autoproteolysis-inducing (GAIN) domain that is proximal to the N terminus of the G protein–coupling seven-transmembrane–spanning bundle. GAIN domain–mediated self-cleavage is constitutive and produces two-fragment holoreceptors that remain bound at the cell surface. It has been of recent interest to understand how AGPCRs are activated in relation to their two-fragment topologies. Dissociation of the AGPCR fragments stimulates G protein signaling through the action of the tethered-peptide agonist stalk that is occluded within the GAIN domain in the holoreceptor form. AGPCRs can also signal independently of fragment dissociation, and a few receptors possess GAIN domains incapable of self-proteolysis. This has resulted in complex theories as to how these receptors are activated in vivo, complicating pharmacological advances. Currently, there is no existing structure of an activated AGPCR to support any of the theories. Further confounding AGPCR research is that many of the receptors remain orphans and lack identified activating ligands. In this review, we provide a detailed layout of the current theorized modes of AGPCR activation with discussion of potential parallels to mechanisms used by other GPCR classes. We provide a classification means for the ligands that have been identified and discuss how these ligands may activate AGPCRs in physiological contexts.

scholarly journals Gab Docking Proteins in Cardiovascular Disease, Cancer, and Inflammation

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Yoshikazu Nakaoka ◽  
Issei Komuro
Keyword(s):  
Cardiovascular Disease ◽  
Tyrosine Phosphatase ◽  
Sh2 Domain ◽  
Regulatory Subunit ◽  
Special Focus ◽  
Protein Signaling ◽  
Physiological Processes ◽  
Docking Proteins ◽  
Src Homology ◽  
Cancer And Inflammation

The docking proteins of the Grb2-associated binder (Gab) family have emerged as crucial signaling compartments in metazoans. In mammals, the Gab proteins, consisting of Gab1, Gab2, and Gab3, are involved in the amplification and integration of signal transduction evoked by a variety of extracellular stimuli, including growth factors, cytokines, antigens, and other molecules. Gab proteins lack the enzymatic activity themselves; however, when phosphorylated on tyrosine residues, they provide binding sites for multiple Src homology-2 (SH2) domain-containing proteins, such as SH2-containing protein tyrosine phosphatase 2 (SHP2), phosphatidylinositol 3-kinase regulatory subunit p85, phospholipase Cγ, Crk, and GC-GAP. Through these interactions, the Gab proteins transduce signals from activated receptors into pathways with distinct biological functions, thereby contributing to signal diversification. They are known to play crucial roles in numerous physiological processes through their associations with SHP2 and p85. In addition, abnormal Gab protein signaling has been linked to human diseases including cancer, cardiovascular disease, and inflammatory disorders. In this paper, we provide an overview of the structure, effector functions, and regulation of the Gab docking proteins, with a special focus on their associations with cardiovascular disease, cancer, and inflammation.

Sign in / Sign up

Export Citation Format

Share Document