Heat capacity changes in heme protein–ligand interactions

Zakariassen, Henrik; Sørlie, Morten

doi:10.1016/j.tca.2007.07.021

Cited by 24 publications

(18 citation statements)

References 35 publications

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“…The dissociation constant (K d ) and the entropy change (⌬S) are obtained by calculation using the equation of ⌬G ϭ ϪRT ln K a and T⌬G ϭ ⌬H Ϫ ⌬G, where ⌬G is free energy change, R is the Faraday constant, and T is absolute temperature. Parameterization of ⌬S was calculated as described previously (42 …”

Section: Methodsmentioning

confidence: 99%

Insights into the Inhibitory Mechanisms of the Regulatory Protein IIAGlc on Melibiose Permease Activity

Hariharan

Guan

2014

Journal of Biological Chemistry

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Background:The phosphotransfer protein IIA Glc plays a key role in the regulation of carbohydrate metabolism. Results: ITC measurements show that IIA Glc binds to melibiose permease at a stoichiometry of unity and inhibits sugar binding affinity and conformational entropy. Conclusion: IIA Glc inhibits MelB by restraining its conformational change. Significance: IIA Glc is a useful tool for structure-function studies of its regulated permeases.

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Section: Methodsmentioning

confidence: 99%

Insights into the Inhibitory Mechanisms of the Regulatory Protein IIAGlc on Melibiose Permease Activity

Hariharan

Guan

2014

Journal of Biological Chemistry

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“…The heat capacity changes observed for the binding of His and Arg to LAOBP (Table ) are more negative than those observed for the rigid‐body binding of small molecules to proteins (~5 to −100 cal mol −1 K −1 ; García‐Hernández et al ., ; Zakariassen and Sørlie, ; Zakariassen et al ., ; Chu et al ., ). In contrast, the Δ Cp b values determined in this work, as well as the few values reported for PBPs in the literature, are large and negative: −376 and −436 cal mol −1 K −1 for the complexes of l ‐galactose and l ‐arabinose with the arabinose binding protein (Fukada et al ., ) and −207 cal mol −1 K −1 for the binding of maltose to the maltose binding protein (Thomson et al ., ).…”

Section: Discussionmentioning

confidence: 98%

On the molecular basis of the high affinity binding of basic amino acids to LAOBP, a periplasmic binding protein from Salmonella typhimurium

Pulido

Silva

Téllez

et al. 2015

J of Molecular Recognition

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The rational designing of binding abilities in proteins requires an understanding of the relationship between structure and thermodynamics. However, our knowledge of the molecular origin of high-affinity binding of ligands to proteins is still limited; such is the case for l-lysine-l-arginine-l-ornithine periplasmic binding protein (LAOBP), a periplasmic binding protein from Salmonella typhimurium that binds to l-arginine, l-lysine, and l-ornithine with nanomolar affinity and to l-histidine with micromolar affinity. Structural studies indicate that ligand binding induces a large conformational change in LAOBP. In this work, we studied the thermodynamics of l-histidine and l-arginine binding to LAOBP by isothermal titration calorimetry. For both ligands, the affinity is enthalpically driven, with a binding ΔCp of ~-300 cal mol(-1) K(-1) , most of which arises from the burial of protein nonpolar surfaces that accompanies the conformational change. Osmotic stress measurements revealed that several water molecules become sequestered upon complex formation. In addition, LAOBP prefers positively charged ligands in their side chain. An energetic analysis shows that the protein acquires a thermodynamically equivalent state with both ligands. The 1000-fold higher affinity of LAOBP for l-arginine as compared with l-histidine is mainly of enthalpic origin and can be ascribed to the formation of an extra pair of hydrogen bonds. Periplasmic binding proteins have evolved diverse energetic strategies for ligand recognition. STM4351, another arginine binding protein from Salmonella, shows an entropy-driven micromolar affinity toward l-arginine. In contrast, our data show that LAOBP achieves nanomolar affinity for the same ligand through enthalpy optimization.

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“…4 Table 2). The measured total reaction ΔS is the net value of ΔS mix + ΔS solv + ΔS conf (48,49). The mixing entropy change ΔS mix can be estimated by ΔS mix = R ln (1/55.5), that is, −33 J/mol·K (48,49).…”

Section: Iiamentioning

confidence: 99%

“…Parameterization of ΔS was calculated as described previously (49,53). Total ΔS = ΔS mix + ΔS solv + ΔS conf .…”

Section: Iiamentioning

confidence: 99%

Thermodynamic mechanism for inhibition of lactose permease by the phosphotransferase protein IIA ^Glc

Hariharan

Balasubramaniam²,

Peterkofsky

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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In a variety of bacteria, the phosphotransferase protein IIA Glc plays a key regulatory role in catabolite repression in addition to its role in the vectorial phosphorylation of glucose catalyzed by the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS). The lactose permease (LacY) of Escherichia coli catalyzes stoichiometric symport of a galactoside with an H + , using a mechanism in which sugar-and H + -binding sites become alternatively accessible to either side of the membrane. Both the expression (via regulation of cAMP levels) and the activity of LacY are subject to regulation by IIA Glc (inducer exclusion). Here we report the thermodynamic features of the IIA Glc -LacY interaction as measured by isothermal titration calorimetry (ITC). The studies show that IIA Glc binds to LacY with a K d of about 5 μM and a stoichiometry of unity and that binding is driven by solvation entropy and opposed by enthalpy. Upon IIA Glc binding, the conformational entropy of LacY is restrained, which leads to a significant decrease in sugar affinity. By suppressing conformational dynamics, IIA Glc blocks inducer entry into cells and favors constitutive glucose uptake and utilization. Furthermore, the studies support the notion that sugar binding involves an induced-fit mechanism that is inhibited by IIA Glc binding. The precise mechanism of the inhibition of LacY by IIA Glc elucidated by ITC differs from the inhibition of melibiose permease (MelB), supporting the idea that permeases can differ in their thermodynamic response to binding IIA Glc .ITC | PTS | sugar/cation symport | protein-protein interactions | protein conformation C arbohydrate uptake in bacteria is catalyzed by a collection of sugar permeases that belong to different families of transport proteins. In Escherichia and Salmonella, the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) carries out both catalytic and regulatory functions and plays a key role in catabolite repression resulting in preferential utilization of glucose (a constitutive process) that is transported by vectorial phosphorylation catalyzed by the PTS (1-5). The phosphotransferase protein IIA Glc plays a direct role in this regulation of inducible transport systems. The lac operon (6) with lacZ encoding β-galactosidase and lacY encoding lactose permease (LacY) and the mel operon (7, 8) with melA encoding α-galactosidase and melB encoding melibiose permease (MelB) are subject to IIA Glc regulation (9-13). Both LacY and MelB catalyze electrogenic symport of a galactoside with a cation (14-21). Expression of the structural genes requires the participation of both a global transcriptional activator (the cAMP-CAP complex) and a specific inducer (lactose or melibiose, respectively) (3, 22, 23). IIA Glc regulates both cAMP (24) and inducer levels, and this study focuses on regulation of LacY, which influences inducer entry into the cell.With maltose permease, an ABC permease also under PTS regulation, two molecules of IIA Glc bind to the cytoplasmic ATPase subunits and c...

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Heat capacity changes in heme protein–ligand interactions

Cited by 24 publications

References 35 publications

Insights into the Inhibitory Mechanisms of the Regulatory Protein IIAGlc on Melibiose Permease Activity

Insights into the Inhibitory Mechanisms of the Regulatory Protein IIAGlc on Melibiose Permease Activity

On the molecular basis of the high affinity binding of basic amino acids to LAOBP, a periplasmic binding protein from Salmonella typhimurium

Thermodynamic mechanism for inhibition of lactose permease by the phosphotransferase protein IIA ^Glc

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Heat capacity changes in heme protein–ligand interactions

Cited by 24 publications

References 35 publications

Insights into the Inhibitory Mechanisms of the Regulatory Protein IIAGlc on Melibiose Permease Activity

Insights into the Inhibitory Mechanisms of the Regulatory Protein IIAGlc on Melibiose Permease Activity

On the molecular basis of the high affinity binding of basic amino acids to LAOBP, a periplasmic binding protein from Salmonella typhimurium

Thermodynamic mechanism for inhibition of lactose permease by the phosphotransferase protein IIA Glc

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Thermodynamic mechanism for inhibition of lactose permease by the phosphotransferase protein IIA ^Glc