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Full-Text Articles in Physical Sciences and Mathematics
Spectroscopic And Functional Characterization Of The Nitric Oxide Adducts Of The Fe(Iii) And Fe(Ii) States Of The Co-Sensing Transcription Factor, Cooa, From Carboxydothermus Hydrogenoformans, Robert Clark, Edra Jani, Arathi Francis, Elise Laroche, Isabel Malone
Spectroscopic And Functional Characterization Of The Nitric Oxide Adducts Of The Fe(Iii) And Fe(Ii) States Of The Co-Sensing Transcription Factor, Cooa, From Carboxydothermus Hydrogenoformans, Robert Clark, Edra Jani, Arathi Francis, Elise Laroche, Isabel Malone
Robert Clark
CooA is a carbon monoxide (CO) sensing transcription factor that is found in several bacteria and regulates CO metabolism. CO binding to CooA’s heme groups initiates a conformation change that activates protein DNA binding. This study investigates the reaction of Fe(III) Carboxydothermus hydrogenoformansCooA (Ch CooA) with nitric oxide (NO). Previously, Clark and coworkers reported Fe(II) Ch CooA bound NO to form a 6-coordinate (6-C) Fe(II)-NO adduct that was active for DNA binding in vivo and in vitro. This is in contrast to the best studied CooA homolog from R. rubrum (Rr) that was exquisitely specific for CO and formed an …
Mechanism Of Redox- And Co-Sensing By The Heme Protein, Cooa: Cryoradiolysis Studies, Robert Clark, Deanna Kalafut
Mechanism Of Redox- And Co-Sensing By The Heme Protein, Cooa: Cryoradiolysis Studies, Robert Clark, Deanna Kalafut
Robert Clark
Gas-sensing heme proteins participate in a variety of signal-transduction mechanisms across a broad range of biological systems. This class of proteins functions by undergoing an allosteric conformational change in response to the binding of a small gas molecule to a heme group. CooA, which is a redox- and CO-sensing transcription factor that is found in several bacteria, regulates gene expression that enables growth on CO as a sole energy source. In the current study, we have employed the technique of gamma-irradiation / cryoreduction spectroscopy (cryoradiolysis) to investigate facile changes that occur to the heme coordination structure of CooA during activation. …
Silica-Bound Copper(Ii) Triazacyclononane As A Phosphate Esterase: Effect Of Linker Length And Surface Hydrophobicity, Brett Bodsgard, Robert Clark, Anthony Ehrbar, Judith Burstyn
Silica-Bound Copper(Ii) Triazacyclononane As A Phosphate Esterase: Effect Of Linker Length And Surface Hydrophobicity, Brett Bodsgard, Robert Clark, Anthony Ehrbar, Judith Burstyn
Robert Clark
A series of silica-bound Cu(II) triazacyclononane materials was prepared to study the effect of linker length and surface hydrophobicity on the hydrolysis of phosphate esters. The general synthetic approach for these heterogeneous reagents was rhodium-catalyzed hydrosilation between an alkenyl-modified triazacyclononane and hydride-modified silica followed by metallation with a Cu(II) salt. Elemental analysis confirmed that organic functionalization of the silica gel was successful and provided an estimate of the surface concentration of triazacyclononane. EPR spectra were consistent with square pyramidal Cu(II), indicating that Cu(II) ions were bound to the immobilized macrocycles. The hydrolytic efficacies of these heterogeneous reagents were tested with …
Impact Of Heme Reconstitution On The Spectroscopic Properties And Dna Binding Activity Of The H82a Variant Of The Carbon Monoxide-Sensing Heme Transcription Factor, Cooa, Rachel Troester, Robert Clark
Impact Of Heme Reconstitution On The Spectroscopic Properties And Dna Binding Activity Of The H82a Variant Of The Carbon Monoxide-Sensing Heme Transcription Factor, Cooa, Rachel Troester, Robert Clark
Robert Clark
CooA is a gas-sensing heme protein that regulates the expression of genes responsible for growth by carbon monoxide (CO) in several bacteria. CO binding to the CooA heme groups results in an allosteric conformation change that initiates the protein’s DNA binding function. All known CooA homologs have a conserved histidine residue that i) acts as the proximal heme ligand and ii) istrans to CO. Together with the results from mutagenesis studies, this observation suggests the presence of a proximal histidine ligand is required for CooA’s DNA-binding activity. However, since mutants lacking this His have been observed to lose heme …
Gas-Binding Studies Of The Carbon Monoxide Sensor, Cooa, Joshua Wagoner, Lindsey Dillingham, Robert Clark
Gas-Binding Studies Of The Carbon Monoxide Sensor, Cooa, Joshua Wagoner, Lindsey Dillingham, Robert Clark
Robert Clark
CooA is a carbon monoxide-sensing (CO-sensing) heme protein transcription factor that regulates gene activation in several bacteria and is a convenient model for studying analogous proteins in the human body. The goal of this study is to understand the specificity and mechanism of gas binding of CooA. To accomplish this, wild type CooA and selected protein variants were purified and then reacted with different diatomic gas molecules. The resulting species were characterized by UV-Visible and fluorescence spectroscopy.
Mutagenesis Studies To Investigate Ligand Binding To The Carbon Monoxide-Sensing Heme Protein, Cooa, From Carboxydothermus Hydrogenoformans, Laura Wagoner, Josh Wagoner, Thomas Goyne, Robert Clark
Mutagenesis Studies To Investigate Ligand Binding To The Carbon Monoxide-Sensing Heme Protein, Cooa, From Carboxydothermus Hydrogenoformans, Laura Wagoner, Josh Wagoner, Thomas Goyne, Robert Clark
Robert Clark
The work reported here is part of a larger effort to determine how amino acid residues that compose the heme pockets of gas-sensing heme proteins impact the proteins’ regulation mechanisms and gas specificity. In the present study, we have employed site-directed mutagenesis to prepare protein variants of the carbon monoxide (CO)-sensing heme protein, CooA, from Carboxydothermus hydrogenoformans. These mutants have been designed in an attempt to rationally alter CooA’s effector specificity. We have prepared, isolated, and purified several protein variants to date, including C80T CooA. The C80T substitution is expected to increase the steric bulk on the proximal face of …
Impact Of Nitric Oxide (No) Treatment On The Spectroscopic Properties And Dna Binding Activity Of The Carbon Monoxide-Sensing Heme Transcription Factor, Cooa, Edra Jani, Robert Clark
Impact Of Nitric Oxide (No) Treatment On The Spectroscopic Properties And Dna Binding Activity Of The Carbon Monoxide-Sensing Heme Transcription Factor, Cooa, Edra Jani, Robert Clark
Robert Clark
CooA is a carbon monoxide (CO)-sensing heme transcription factor that regulates CO metabolism in several bacteria including Carboxydothermus hydrogenoformans (Ch). The goal of this research was to investigate the spectroscopic properties and DNA binding activity of Fe(III) Ch CooA that was reacted with NO. Based on electronic absorbance spectra, addition of NO to Fe(III) CooA resulted in the formation of a 6-coordinate (6-C) Fe(III)-NO intermediate species, which slowly converted to a 5-coordinate (5-C) Fe(II)-NO complex. A fluorescence anisotropy assay revealed appreciable DNA binding activity by the 6-C Fe(III)-NO form and lesser activity by the 5-C adduct. DNA binding by 5-C …