Oligomeric state affects oxygen dissociation and diguanylate cyclase activity of globin coupled sensors

2014 ◽  
Vol 10 (11) ◽  
pp. 2823-2826 ◽  
Author(s):  
Justin L. Burns ◽  
D. Douglas Deer ◽  
Emily E. Weinert
Keyword(s):  
Enzyme Catalysis ◽  
Cyclase Activity ◽  
Oxygen Binding ◽  
Diguanylate Cyclase ◽  
Oligomeric State ◽  
Oxygen Dissociation

Globin coupled sensors exist as a mixture of oligomeric states, which affect both enzyme catalysis and oxygen binding.

Influence of carbon monoxide on hemoglobin-oxygen binding

1976 ◽  
Vol 41 (6) ◽  
pp. 893-899 ◽  
Author(s):  
M. P. Hlastala ◽  
H. P. McKenna ◽  
R. L. Franada ◽  
J. C. Detter
Keyword(s):  
Carbon Monoxide ◽  
Oxygen Affinity ◽  
Co2 Concentration ◽  
Bohr Effect ◽  
Oxygen Binding ◽  
Dissociation Curve ◽  
Low Oxygen ◽  
Oxygen Dissociation ◽  
Initial Binding ◽  
Fixed Acid

The oxygen dissociation curve and Bohr effect were measured in normal whole blood as a function of carboxyhemoglobin concentration [HbCO]. pH was changed by varying CO2 concentration (CO2 Bohr effect) or by addition of isotonic NaOH or HCl at constant PCO2 (fixed acid Bohr effect). As [HbCO] varied through the range of 2, 25, 50, and 75%, P50 was 26.3, 18.0, 11.6, and 6.5 mmHg, respectively. CO2 Bohr effect was highest at low oxygen saturations. This effect did not change as [HbCO] was increased. However, as [HbCO] was increased from 2 to 75%, the fixed acid Bohr factor increased in magnitude from -0.20 to -0.80 at very low oxygen saturations. The effect of molecular CO2 binding (carbamino) on oxygen affinity was eliminated at high [HbCO]. These results are consistent with the initial binding of O2 or CO to thealpha-chain of hemoglobin. The results also suggest that heme-heme interaction is different for oxygen than for carbon monoxide.

Myoglobin oxygen dissociation by multiwavelength spectroscopy

1997 ◽  
Vol 82 (1) ◽  
pp. 86-92 ◽  
Author(s):  
Kenneth A. Schenkman ◽  
David R. Marble ◽  
David H. Burns ◽  
Eric O. Feigl
Keyword(s):  
Least Squares ◽  
Hill Equation ◽  
Oxygen Binding ◽  
Dissociation Curve ◽  
Nitrogen Gas ◽  
Binding Characteristics ◽  
Oxygen Fraction ◽  
Oxygen Dissociation ◽  
Dissociation Curves ◽  
The Hill

Schenkman, Kenneth A., David R. Marble, David H. Burns, and Eric O. Feigl. Myoglobin oxygen dissociation by multiwavelength spectroscopy. J. Appl. Physiol. 82(1): 86–92, 1997.—Multiwavelength optical spectroscopy was used to determine the oxygen-binding characteristics for equine myoglobin. Oxygen-binding relationships as a function of oxygen tension were determined for temperatures of 10, 25, 35, 37, and 40°C, at pH 7.0. In addition, dissociation curves were determined at 37°C for pH 6.5, 7.0, and 7.5. Equilibration was achieved with a myoglobin solution, at the desired temperature and pH, and 16 oxygen-nitrogen gas mixtures of known oxygen fraction. Correction for the inevitable presence of metmyoglobin was made by using a three-component least squares analysis and by correcting the end point oxymyoglobin spectra for the presence of metmyoglobin. The[Formula: see text] at which myoglobin is half-saturated with O2(P50) was determined to be 2.39 Torr at pH 7.0 and 37°C. The myoglobin dissociation curve was well fit by the Hill equation [saturation =[Formula: see text]/([Formula: see text]+ P50)].

scholarly journals Subcellular Clustering of the Phosphorylated WspR Response Regulator Protein Stimulates Its Diguanylate Cyclase Activity

mBio ◽  
2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Varisa Huangyutitham ◽  
Zehra Tüzün Güvener ◽  
Caroline S. Harwood
Keyword(s):  
Signal Transduction ◽  
Biofilm Formation ◽  
Response Regulator ◽  
Cluster Formation ◽  
Cyclase Activity ◽  
Diguanylate Cyclase ◽  
Regulator Protein ◽  
Response Regulator Protein

ABSTRACT WspR is a hybrid response regulator-diguanylate cyclase that is phosphorylated by the Wsp signal transduction complex in response to growth of Pseudomonas aeruginosa on surfaces. Active WspR produces cyclic di-GMP (c-di-GMP), which in turn stimulates biofilm formation. In previous work, we found that when activated by phosphorylation, yellow fluorescent protein (YFP)-tagged WspR forms clusters that are visible in individual cells by fluorescence microscopy. Unphosphorylated WspR is diffuse in cells and not visible. Thus, cluster formation is an assay for WspR signal transduction. To understand how and why WspR forms subcellular clusters, we analyzed cluster formation and the enzymatic activities of six single amino acid variants of WspR. In general, increased cluster formation correlated with increased in vivo and in vitro diguanylate cyclase activities of the variants. In addition, WspR specific activity was strongly concentration dependent in vitro, and the effect of the protein concentration on diguanylate cyclase activity was magnified when WspR was treated with the phosphor analog beryllium fluoride. Cluster formation appears to be an intrinsic property of phosphorylated WspR (WspR-P). These results support a model in which the formation of WspR-P subcellular clusters in vivo in response to a surface stimulus is important for potentiating the diguanylate cyclase activity of WspR. Subcellular cluster formation appears to be an additional means by which the activity of a response regulator protein can be regulated. IMPORTANCE Bacterial sensor proteins often phosphorylate cognate response regulator proteins when stimulated by an environmental signal. Phosphorylated response regulators then mediate an appropriate adaptive cellular response. About 6% of response regulator proteins have an enzymatic domain that is involved in producing or degrading cyclic di-GMP (c-di-GMP), a molecule that stimulates bacterial biofilm formation. In this work, we examined the in vivo and in vitro behavior of the response regulator-diguanylate cyclase WspR. When phosphorylated in response to a signal associated with surface growth, WspR has a tendency to form oligomers that are visible in cells as subcellular clusters. Our results show that the formation of phosphorylated WspR (WspR-P) subcellular clusters is important for potentiating the diguanylate cyclase activity of WspR-P, making it more active in c-di-GMP production. We conclude that oligomer formation visualized as subcellular clusters is an additional mechanism by which the activities of response regulator-diguanylate cyclases can be regulated.

Physiological variation of mouse haemoglobins

1983 ◽  
Vol 218 (1213) ◽  
pp. 443-453 ◽  
Keyword(s):  
Natural Populations ◽  
Oxygen Affinity ◽  
Strain Differences ◽  
Inbred Strains ◽  
Oxygen Binding ◽  
Differential Survival ◽  
Oxygen Dissociation ◽  
The Mean ◽  
Oxygen Carrying Capacity ◽  
Β Chain

Polymorphism at Hbb (haemoglobin β-chain) is widespread in natural populations of the house mouse, Mus musculus , and appears to be maintained by natural selection. This report is an attempt to correlate genotypic fluctuations at Hbb with a most important physiological attribute of haemoglobin, its oxygen carrying capacity. Oxygen affinity has been studied and P 50 values have been measured in 12 inbred strains as well as wild-caught mice from Skokholm island. The mean P 50 of each inbred strain is a constant characteristic, although there is high within-strain variation and the oxygen affinity of the blood of an individual can fluctuate considerably from week to week. The causes of this variation remain obscure but neither within-strain nor between-strain differences are correlated with known modulators of oxygen binding. In general, the blood of mice of inbred strains as well as wild-caught mice that are homozygous for Hbb d tends to have a higher oxygen affinity than that from comparable animals homozygous for Hbb 8 , but it seems likely that the oxygen dissociation properties of haemoglobin are not the only ones important in determining differential survival of a particular Hbb type under varying environmental stress.

scholarly journals Partial oxygen-dissociation of crystalline giant hemoglobin

2014 ◽  
Vol 70 (a1) ◽  
pp. C474-C474 ◽  
Author(s):  
Nobutaka Numoto ◽  
Taro Nakagawa ◽  
Akiko Kita ◽  
Nobutoshi Ito ◽  
Yoshihiro Fukumori ◽  
...  
Keyword(s):  
Structural Changes ◽  
Quaternary Structure ◽  
Oxygen Binding ◽  
Nitrogen Gas ◽  
Soaking Time ◽  
Allosteric Mechanism ◽  
Oxygen Dissociation ◽  
Intermediate States ◽  
Complete Dissociation ◽  
Partial Oxygen

Allosteric oxygen-binding of hemoglobin (Hb) has been widely discussed based on the quaternary structural changes elucidated by the crystal structures of the oxygenated and deoxygenated states. However, it remains to be determined the structure of intermediate states between the oxy and deoxy forms without any artificial modification of the Hb molecule. A tubeworm, Lamellibrachia satsuma has extracellular giant hemoglobins with a molecular mass of about 400 and 3,600 kDa. Recently, we have determined the crystal structure of the 400 kDa Hb (V2Hb) in the oxy state, and then we successfully obtained the deoxygenated crystals of V2Hb from oxy crystals by the soaking methods [1]. These findings encourage us to initiate structural studies for the intermediate states between the oxy and deoxy forms of V2Hb, which should provide a more accurate understanding of the allosteric mechanism of Hbs. The deoxy crystals of V2Hb were obtained from oxy crystals through the soaking in a solution containing 50 mM sodium hydrosulfite, and incubated for a few minutes. We tested various soaking times from 3 s to 180 s and then immediately flash-frozen under a nitrogen gas stream. The obtained structures reveal that in the case of the soaking time was longer than 10 s, the electron densities of the oxygen molecules at some heme pockets (oxygen binding sites) were very week or disappeared. These `intermediate' structures show almost the same quaternary structure as that of the oxy structure. This fact suggests that quaternary rearrangement of V2Hb might arise just before a complete dissociation of all the oxygen molecules from all the subunits.

scholarly journals Hemoglobin in Frankia, a Nitrogen-Fixing Actinomycete

2002 ◽  
Vol 68 (5) ◽  
pp. 2629-2631 ◽  
Author(s):  
John D. Tjepkema ◽  
Robert E. Cashon ◽  
Jason Beckwith ◽  
Christa R. Schwintzer
Keyword(s):  
Optical Absorption ◽  
Rate Constant ◽  
Dissociation Rate ◽  
Oxygen Binding ◽  
Association Rate Constant ◽  
Association Rate ◽  
Absorption Bands ◽  
Oxygen Dissociation ◽  
Equilibrium Oxygen ◽  
Strain Cci3

ABSTRACT Frankia strain CcI3 grown in culture produced a hemoglobin which had optical absorption bands typical of a hemoglobin and a molecular mass of 14.1 kDa. Its equilibrium oxygen binding constant was 274 nM, the oxygen dissociation rate constant was 56 s−1, and the oxygen association rate constant was 206 μM−1 s−1.

scholarly journals Escherichia coli K-12 YfgF is an anaerobic cyclic di-GMP phosphodiesterase with roles in cell surface remodelling and the oxidative stress response

Microbiology ◽  
2010 ◽  
Vol 156 (9) ◽  
pp. 2873-2886 ◽  
Author(s):  
Melissa M. Lacey ◽  
Jonathan D. Partridge ◽  
Jeffrey Green
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Cell Surface ◽  
Regulatory Networks ◽  
Oxidative Stress Response ◽  
Cyclase Activity ◽  
Diguanylate Cyclase ◽  
Phosphodiesterase Activity ◽  
K 12

The Escherichia coli K-12 yfgF gene encodes a protein with domains associated with cyclic di-GMP signalling: GGDEF (associated with diguanylate cyclase activity) and EAL (associated with cyclic di-GMP phosphodiesterase activity). Here, it is shown that yfgF is expressed under anaerobic conditions from a class II FNR (regulator of fumarate and nitrate reduction)-dependent promoter. Anaerobic expression of yfgF is greatest in stationary phase, and in cultures grown at 28 °C, suggesting that low growth rates promote yfgF expression. Mutation of yfgF resulted in altered cell surface properties and enhanced sensitivity when anaerobic cultures were exposed to peroxides. The purified YfgF GGDEF-EAL (YfgFGE) and EAL (YfgFE) domains possessed cyclic di-GMP-specific phosphodiesterase activity, but lacked diguanylate cyclase activity. However, the catalytically inactive GGDEF domain was required for YfgFGE dimerization and enhanced cyclic di-GMP phosphodiesterase activity in the presence of physiological concentrations of Mg2+. The cyclic di-GMP phosphodiesterase activity of YfgFGE and YfgFE was inhibited by the product of the reaction, 5′-phosphoguanylyl-(3′–5′)-guanosine (pGpG). Thus, it is shown that the yfgF gene encodes an anaerobic cyclic di-GMP phosphodiesterase that is involved in remodelling the cell surface of E. coli K-12 and in the response to peroxide shock, with implications for integrating three global regulatory networks, i.e. oxygen regulation, cyclic di-GMP signalling and the oxidative stress response.

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