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Fahui Li,
Pan Shi,
Jiasong Li,
Fan Yang,
Tianyuan Wang,
Wei Zhang,
Feng Gao,
Wei Ding,
Dong Li,
Juan Li,
Ying Xiong,
Jinpeng Sun,
Weimin Gong, Changlin Tian,
Jiangyun Wang
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ABSTRACT: Simple and selective: Tyrosine phosphorylation is a pivotal post-translational modification which regulates the enzymatic activity, protein conformation, and protein-protein interactions. The highly efficient genetic incorporation of 3,5-difluorotyrosine (F2Y) in E. coli and the use of F2Y as a 19 F NMR probe for the tyrosine phosphorylation are reported.
Angewandte Chemie International Edition 02/2013; · 13.45 Impact Factor
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ABSTRACT: Integrin proteins are very important adhesion receptors that mediate cell-cell and cell-extracellular matrix interactions. They play essential roles in cell signaling and the regulation of cellular shape, motility, and the cell cycle. Here, the transmembrane and cytoplasmic (TMC) domains of integrin α1 and β1 were over-expressed and purified in detergent micelles. The structure and backbone relaxations of α1-TMC in LDAO micelles were determined and analyzed using solution NMR. A long helix, extending from the transmembrane region to the cytoplasmic tail, was observed in α1-TMC. Structural comparisons of α1-TMC with reported αIIb-TMC domains indicated different conformations in the transmembrane regions and cytoplasmic tails. An NMR titration experiment indicated weak interactions between α1-TMC and β1-TMC through several α1-TMC residues located at its N-terminal juxta-transmembrane region and C-terminal extended helix region.
PLoS ONE 01/2013; 8(4):e62954. · 4.09 Impact Factor
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ABSTRACT: In this report, (19)F spin incorporation in a specific site of a specific membrane protein in E. coli was accomplished via trifluoromethyl-phenylalanine ((19) F-tfmF). Site-specific (19)F chemical shifts and longitudinal relaxation times of diacylglycerol kinase (DAGK), an E. coli membrane protein, were measured in its native membrane using in situ magic angle spinning (MAS) solid state nuclear magnetic resonance (NMR). Comparing with solution NMR data of the purified DAGK in detergent micelles, the in situ MAS-NMR data illustrated that (19)F chemical shift values of residues at different membrane protein locations were influenced by interactions between membrane proteins and their surrounding lipid or lipid mimic environments, while (19)F side chain longitudinal relaxation values were probably affected by different interactions of DAGK with planar lipid bilayer versus globular detergent micelles.
Protein Science 02/2012; 21(4):596-600. · 2.80 Impact Factor
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ABSTRACT: Abscisic acid (ABA) is one of the most essential phytohormones, and plays an important role in growth and development regulation, as well as in stress responses. The PYR/PYL/RCAR family (PYL for short)-comprised of 14 proteins in Arabidopsis-was recently identified as soluble ABA receptors that function in the perception and transduction of ABA signaling. In this work, the crystal structures of PYL10 were determined in the apo- and ABA-bound states, with respective resolutions of 3.0 and 2.7Å. Surprisingly, a closed CL2 conformation was observed in the apo-PYL10 structure, which was different from a previously reported open CL2 conformation. A putative two-conformation dynamical equilibrium model was proposed to explain PYL10's constitutive binding to PP2Cs in the apo-state and its increased PP2C binding ability in the ABA-bound state.
Biochemical and Biophysical Research Communications 02/2012; 418(1):122-7. · 2.48 Impact Factor
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ABSTRACT: Rv0899 from Mycobacterium tuberculosis belongs to the OmpA (outer membrane protein A) family of outer membrane proteins. It functions as a pore-forming protein; the deletion of this gene impairs the uptake of some water-soluble substances, such as serine, glucose, and glycerol. Rv0899 has also been shown to play a part in low-pH environment adaption, which may play a part in pathogenic mycobacteria overcoming the host's defense mechanisms. Based on many bacterial physiological data and recent structural studies, it was proposed that Rv0899 forms an oligomeric channel to carry out such functions. In this work, biochemical and structural data obtained from solution NMR and EPR spectroscopy indicated that Rv0899 is a monomeric membrane-anchoring protein with two separate domains, rather than an oligomeric pore. Using NMR chemical shift perturbation and isothermal calorimetric titration assays, we show that Rv0899 was able to interact with Zn(2+) ions, which may indicate a role for Rv0899 in the process of Zn(2+) acquisition.
Journal of Molecular Biology 11/2011; 415(2):382-92. · 4.00 Impact Factor
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ABSTRACT: Membrane proteins play an essential role in cellular metabolism, transportation and signal transduction across cell membranes. The scarcity of membrane protein structures has thus far prevented a full understanding of their molecular mechanisms. Preliminary topology studies and residue solvent exposure analysis have the potential to provide valuable information on membrane proteins of unknown structure. Here, a (19)F-containing unnatural amino acid (trimethylfluoro-phenylalanine, tfmF) was applied to accomplish site-specific (19)F spin incorporation at different sites in diacylglycerol kinase (DAGK, an Escherichia coli membrane protein) for site-specific solvent exposure analysis. Due to isotope effect on (19)F spins, a standard curve for (19)F-tfmF chemical shifts was drawn for varying solvent H(2)O/D(2)O ratios. Further site-specific (19)F solvent isotope shift analysis was conducted for DAGK to distinguish residues in water-soluble loops, interfacial areas or hydrophobic membrane regions. This site-specific solvent exposure analysis method could be applied for further topological analysis of other membrane proteins.
Biochemical and Biophysical Research Communications 09/2011; 414(2):379-83. · 2.48 Impact Factor
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Xue Yang,
Xingqiao Xie,
Liu Chen,
Hao Zhou,
Zheng Wang,
Weijing Zhao,
Ran Tian,
Rongguang Zhang, Changlin Tian,
Jiafu Long,
Yuequan Shen
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ABSTRACT: The establishment of epithelial cell polarity requires the assembly of multiprotein complexes and is crucial during epithelial morphogenesis. Three scaffolding proteins, Dlg1, MPP7, and Mals3, can be assembled to form a complex that functions in the establishment and maintenance of apicobasal polarity in epithelial tissues through their L27 domains. Here we report the crystal structure of a 4-L27-domain complex derived from the human tripartite complex Dlg1-MPP7-Mals3 in combination with paramagnetic relaxation enhancement measurements. The heterotrimer consists of 2 pairs of heterodimeric L27 domains. These 2 dimers are asymmetric due to the large difference between the N- and C-terminal tandem L27 domain of MPP7. Structural analysis combined with biochemical experiments further reveals that the loop αA-αB and helix αB of the C-terminal L27 domain of MPP7 play a critical role in assembling the entire tripartite complex, suggesting a synergistic tandem L27-mediated assembling event.
The FASEB Journal 12/2010; 24(12):4806-15. · 5.71 Impact Factor
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ABSTRACT: Rv1698 has been reported to be an important outer membrane channel protein of Mycobacterium tuberculosis with unknown function. Recombinant Rv1698 overexpressed in Escherichia coli was purified in detergent solution and crystallized at 295 K using the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant. The crystals of Rv1698 diffracted to 2.5 Å resolution and belonged to the orthorhombic space group P422, with unit-cell parameters a = b = 122.0, c = 88.9 Å.
Acta Crystallographica Section F Structural Biology and Crystallization Communications 11/2010; 66(Pt 11):1525-7. · 0.51 Impact Factor
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ABSTRACT: Site-specific ¹⁹F chemical shift and side chain relaxation analysis can be applied on large size proteins. Here, one-dimensional ¹⁹F spectra and T₁, T₂ relaxation data were acquired on a SH3 domain in aqueous buffer containing 60% glycerol, and a nine-transmembrane helices membrane protein diacyl-glycerol kinase (DAGK) in dodecyl phosphochoine (DPC) micelles. The high quality of the data indicates that this method can be applied to site-specifically analyze side chain internal mobility of membrane proteins or large size proteins.
Protein Science 11/2010; 20(1):224-8. · 2.80 Impact Factor
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ABSTRACT: MiRP1 (MinK related protein 1) is a membrane protein in the KCNE family. It can associate with and modulate various voltage gated potassium channels. Mutations in human MiRP1 have been found to cause many congenital and acquired long QT syndromes, which are potentially life-threatening cardiac arrhythmias. Here, human MiRP1 was over-expressed in Escherichia coli, purified and eluted into different detergents. Two dimensional (1)H-(15)N correlated solution nuclear magnetic resonance (NMR) spectra of the human MiRP1 in four different detergent micelles indicated that high resolution solution NMR spectrum can be obtained for human MiRP1 in detergent lyso-myristoylphosphatidylglycerol (LMPG). Circular dichroism (CD) spectroscopy of human MiRP1 indicated a high content of alpha-helical secondary structure in LMPG. Backbone assignments of most MiRP1 residues were achieved through a series of triple resonance NMR experiments. Secondary structure analysis based on backbone chemical shifts showed several stretches of alpha-helices along the primary sequence of MiRP1 in LMPG.
Protein Expression and Purification 11/2010; 76(2):205-10. · 1.59 Impact Factor
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ABSTRACT: SH3 is a ubiquitous domain mediating protein-protein interactions. Recent solution NMR structural studies have shown that a proline-rich peptide is capable of binding to the human vinexin SH3 domain. Here, an orthogonal amber tRNA/tRNA synthetase pair for (15)N/(19)F-trifluoromethyl-phenylalanine ((15)N/(19)F-tfmF) has been applied to achieve site-specific labeling of SH3 at three different sites. One-dimensional solution NMR spectra of backbone amide ((15)N)(1)H and side-chain (19)F were obtained for SH3 with three different site-specific labels. Site-specific backbone amide ((15)N)(1)H and side-chain (19)F chemical shift and relaxation analysis of SH3 in the absence or presence of a peptide ligand demonstrated different internal motions upon ligand binding at the three different sites. This site-specific NMR analysis might be very useful for studying large-sized proteins or protein complexes.
Biochemical and Biophysical Research Communications 10/2010; 402(3):461-6. · 2.48 Impact Factor
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ABSTRACT: Zinc finger motif contains a zinc ion coordinated by several conserved amino acid residues. Yeast Sgf73 protein was identified as a component of SAGA (Spt/Ada/Gcn5 acetyltransferase) multi-subunit complex and Sgf73 protein was known to contain two zinc finger motifs. Sgf73(1-104), containing the first zinc finger motif, was necessary to modulate the deubiquitinase activity of SAGA complex. Here, Sgf73(1-104) was over-expressed using bacterial expression system and purified for solution NMR (nuclear magnetic resonance) structural studies. Secondary structure and site-specific relaxation analysis of Sgf73(1-104) were achieved after solution NMR backbone assignment. Solution NMR and circular dichroism analysis of Sgf73(1-104) after zinc ion removal using chelation reagent EDTA (ethylene-diamine-tetraacetic acid) demonstrated that zinc ion was required to maintain stable conformation of the zinc finger motif.
Biochemical and Biophysical Research Communications 07/2010; 397(3):436-40. · 2.48 Impact Factor
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ABSTRACT: In membrane protein biochemical and structural studies, detergents are used to mimic membrane environment and maintain functional, stable conformation of membrane proteins in the absence of lipid bilayers. However, detergent concentration, esp. molar ratio of membrane protein to detergent is usually unknown. Here, a gas chromatography-mass spectrometry selected ion monitoring (GC-MS-SIM) method was developed to quantify four detergents which are frequently used in membrane protein structural studies. To remove excessive detergents, a filtered centrifugation using Centricon tubes was applied. A membrane protein Ig-Beta fragment in four different detergent micelles was exemplified. Detergent concentrations in the upper and lower fraction of the Centricon tube were measured after each round of centrifugation. The results were very consistent to basic properties of detergent micelles in aqueous solvents. Therefore, coupling of GC-MS-SIM and detergent removal by Centricon tubes, detergents concentration, esp. molar ratio of membrane protein to detergent could be controlled, which will expedite membrane protein structural and biochemical studies.
Protein Expression and Purification 08/2009; 68(2):221-5. · 1.59 Impact Factor
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ABSTRACT: Inwardly rectifying potassium channel 2.3 (Kir2.3) is specifically targeted on the basolateral membranes of epithelial and neuronal cells, and it thus plays an important role in maintaining potassium homeostasis. Tax-interacting protein-1 (TIP-1), an atypical PDZ-domain-containing protein, binds to Kir2.3 with a high affinity, causing the intracellular accumulation of Kir2.3 in cultured epithelial cells. However, the molecular basis of the TIP-1/Kir2.3 interaction is still poorly understood. Here, we present the crystal structure of TIP-1 in complex with the C-terminal Kir2.3-peptide (residues 436-445) to reveal the molecular details of the interaction between them. Moreover, isothermal titration calorimetry experiments show that the C-terminal Kir2.3-peptide binds much more strongly to TIP-1 than to mammalian Lin-7, indicating that TIP-1 can compete with mammalian Lin-7 to uncouple Kir2.3 from its basolateral membrane anchoring complex. We further show that the phosphorylation/dephosphorylation of Ser443 within the C-terminal Kir2.3 PDZ-binding motif RRESAI dynamically regulates the Kir2.3/TIP-1 association in heterologous HEK293T cells. These data suggest that TIP-1 may act as an important regulator for the endocytic pathway of Kir2.3.
Journal of Molecular Biology 08/2009; 392(4):967-76. · 4.00 Impact Factor
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ABSTRACT: The gene SA239 from Staphylococcus aureus encodes a ribokinase that catalyzes the phosphorylation of D-ribose to produce ribose-5-phosphate. Sa239 was crystallized using the hanging-drop vapour-diffusion method. The crystals diffracted to 2.9 A resolution and belonged to space group P6(1)22 or P6(5)22, with unit-cell parameters a = b = 91.8, c = 160.7 A. Preliminary crystallographic analysis revealed that the Matthews coefficient V(M) was 3.01 A(3) Da(-1), indicating the presence of one molecule in the asymmetric unit.
Acta Crystallographica Section F Structural Biology and Crystallization Communications 07/2009; 65(Pt 6):574-6. · 0.51 Impact Factor
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ABSTRACT: Tax-interacting protein-1 (TIP-1) is an unusual signaling protein, containing a single PDZ domain. TIP-1 is able to bind beta-catenin with high affinity and thus inhibit its transcriptional activity. The high-resolution crystal structure of TIP-1 in complex with the C-terminal peptide of beta-catenin provides molecular details for the recognition of beta-catenin by TIP-1. Moreover, structural comparison of peptide-free and peptide-bound TIP-1 reveals that significant conformational changes are required in the betaB-betaC loop region of TIP-1 to avoid clashes with the incoming C-terminal beta-catenin peptide. Such conformational changes have not been observed in other structures of PDZ domains. In addition to the canonical peptide-binding pocket of the PDZ domain, TIP-1 can form a binding cavity to anchor more amino acids through a conserved hydrophobic residue pair (Trp776 of beta-catenin and Pro45 of TIP-1). Structural and biochemical data indicate that the canonical binding pocket together with the hydrophobic residue pair are presumably the major cause of the significantly higher affinity of the beta-catenin C-terminal to TIP-1 than to other PDZ domains, providing a unique binding specificity. Our results reveal the molecular mechanism of TIP-1 as an antagonist in PDZ domain signaling.
Journal of Molecular Biology 10/2008; 384(1):255-63. · 4.00 Impact Factor
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ABSTRACT: A novel and reliable gas chromatography-flame ionization detection (GC-FID) method that can separate and quantify detergents frequently used in membrane protein structural studies has been developed. Different detergents were identified through FID peaks with different retention times. A quadratic regression curve was found to fit the integrated FID peak area against different detergent concentrations. Detergents can be quantified as low as the nanogram level: lauryl-dimethylamine-N-oxide (LDAO), 5 ng; dodecyl maltoside (DDM), 10 ng; and dodecyl phosphocholine (DPC), 50 ng. This method can be applied directly to measure detergent concentration and molar ratio of membrane protein to detergents during membrane protein extraction, purification, concentration, and crystallization.
Analytical Biochemistry 10/2008; 383(2):326-8. · 3.00 Impact Factor
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ABSTRACT: Tax-interacting protein-1 (TIP-1) is an unusual signaling protein, containing a single PDZ domain. TIP-1 is able to bind β-catenin with high affinity and thus inhibit its transcriptional activity. The high-resolution crystal structure of TIP-1 in complex with the C-terminal peptide of β-catenin provides molecular details for the recognition of β-catenin by TIP-1. Moreover, structural comparison of peptide-free and peptide-bound TIP-1 reveals that significant conformational changes are required in the βB-βC loop region of TIP-1 to avoid clashes with the incoming C-terminal β-catenin peptide. Such conformational changes have not been observed in other structures of PDZ domains. In addition to the canonical peptide-binding pocket of the PDZ domain, TIP-1 can form a binding cavity to anchor more amino acids through a conserved hydrophobic residue pair (Trp776 of β-catenin and Pro45 of TIP-1). Structural and biochemical data indicate that the canonical binding pocket together with the hydrophobic residue pair are presumably the major cause of the significantly higher affinity of the β-catenin C-terminal to TIP-1 than to other PDZ domains, providing a unique binding specificity. Our results reveal the molecular mechanism of TIP-1 as an antagonist in PDZ domain signaling.
Journal of Molecular Biology - J MOL BIOL. 01/2008; 384(1):255-263.
