Dataset Information

Characterization of the estradiol-binding site structure of human pancreas-specific protein disulfide isomerase: indispensable role of the hydrogen bond between His278 and the estradiol 3-hydroxyl group.

ABSTRACT: Estradiol (E(2)), a female sex hormone, has important biological functions. Human pancreas-specific protein disulfide isomerase (PDIp), a protein folding catalyst, was recently found to be able to bind E(2). Here we report the characterization of its E(2)-binding site by using biochemical methods coupled with molecular modeling tools. Analysis of various truncated PDIp proteins showed that the b-b' fragment contains an intact E(2)-binding site that has the same binding affinity as the full-length PDIp protein, with apparent K(d) values of approximately 170 nM. Computational modeling and docking analyses revealed that the E(2)-binding site in the b-b' fragment is located in a hydrophobic pocket composed mainly of the b' domain and partially of the b domain. The hydrogen bond, formed between the 3-hydroxyl group of E(2) (donor) and PDIp's His278 (acceptor), is indispensable for its binding. By contrast, the 17?-hydroxyl group of E(2) is of negligible importance for E(2) binding. This binding model was jointly confirmed by a series of experiments, such as selective mutation of the binding site amino acid residues and selective modification of the ligand structures.

SUBMITTER: Fu XM

PROVIDER: S-EPMC3070202 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Characterization of the estradiol-binding site structure of human pancreas-specific protein disulfide isomerase: indispensable role of the hydrogen bond between His278 and the estradiol 3-hydroxyl group.

Fu Xin-Miao XM Wang Pan P Zhu Bao Ting BT

Biochemistry 20101214 1

Estradiol (E(2)), a female sex hormone, has important biological functions. Human pancreas-specific protein disulfide isomerase (PDIp), a protein folding catalyst, was recently found to be able to bind E(2). Here we report the characterization of its E(2)-binding site by using biochemical methods coupled with molecular modeling tools. Analysis of various truncated PDIp proteins showed that the b-b' fragment contains an intact E(2)-binding site that has the same binding affinity as the full-lengt ...[more]

PMID: 21080683

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Project description:Computational studies are performed to analyze the physical properties of hydrogen bonds donated by Tyr16 and Asp103 to a series of substituted phenolate inhibitors bound in the active site of ketosteroid isomerase (KSI). As the solution pK(a) of the phenolate increases, these hydrogen bond distances decrease, the associated nuclear magnetic resonance (NMR) chemical shifts increase, and the fraction of protonated inhibitor increases, in agreement with prior experiments. The quantum mechanical/molecular mechanical calculations provide insight into the electronic inductive effects along the hydrogen bonding network that includes Tyr16, Tyr57, and Tyr32, as well as insight into hydrogen bond coupling in the active site. The calculations predict that the most-downfield NMR chemical shift observed experimentally corresponds to the Tyr16-phenolate hydrogen bond and that Tyr16 is the proton donor when a bound naphtholate inhibitor is observed to be protonated in electronic absorption experiments. According to these calculations, the electronic inductive effects along the hydrogen bonding network of tyrosines cause the Tyr16 hydroxyl to be more acidic than the Asp103 carboxylic acid moiety, which is immersed in a relatively nonpolar environment. When one of the distal tyrosine residues in the network is mutated to phenylalanine, thereby diminishing this inductive effect, the Tyr16-phenolate hydrogen bond becomes longer and the Asp103-phenolate hydrogen bond shorter, as observed in NMR experiments. Furthermore, the calculations suggest that the differences in the experimental NMR data and electronic absorption spectra for pKSI and tKSI, two homologous bacterial forms of the enzyme, are due predominantly to the third tyrosine that is present in the hydrogen bonding network of pKSI but not tKSI. These studies also provide experimentally testable predictions about the impact of mutating the distal tyrosine residues in this hydrogen bonding network on the NMR chemical shifts and electronic absorption spectra.

Dataset Information

Characterization of the estradiol-binding site structure of human pancreas-specific protein disulfide isomerase: indispensable role of the hydrogen bond between His278 and the estradiol 3-hydroxyl group.

Publications

Characterization of the estradiol-binding site structure of human pancreas-specific protein disulfide isomerase: indispensable role of the hydrogen bond between His278 and the estradiol 3-hydroxyl group.

Similar Datasets

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