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Abstract
The binding of the calcium-regulatory protein calmodulin (CaM) to caldesmon (CaD) contributes to the regulation of smooth muscle contraction. Two regions of caldesmon have been identified as putative calmodulin-binding domains. We have earlier reported on the binding of one of these domains to calmodulin (Zhang & Vogel (1994) Biochemistry 33, 1163-1171). Here we have studied the binding of CaM to synthetic peptides of CaD which contain: (1) both the first and second CaM-binding domains; (2) the second CaM-binding domain; and (3) the sequence between the first and second CaM-binding domains. Two-dimensional transferred nuclear Overhauser enhancement proton NMR measurements as well as circular dichroism studies of a 22-residue peptide NKETAGLKVGVSSRINEWLTK, which contains the second CaM-binding domain, show that only the C-terminal half of the peptide becomes alpha-helical upon binding to CaM. Somewhat surprisingly, the shorter 9-residue peptide SRINEWLTK was sufficient to form a 1:1 complex with CaM; this peptide appears to bind as a 3(10)-helix. Proton-carbon-13 correlation NMR titration studies with specifically labeled [methyl-13C]methionine CaM were used to study the participation of the hydrophobic regions in both domains of the dumbbell shaped CaM in peptide binding. Binding of a 54-residue CaD peptide containing both CaM-binding domains affects all the 8 Met residues in the two hydrophobic domains of CaM (only Met 76 in the linker region of CaM is not involved), while binding of the second CaM-binding domain of CaD influences principally Met 51, 71, and Met 124, 144. Simultaneous binding to CaM of two peptides comprising the first and the second CaM-binding domains also caused changes to all Met residues except Met 76. Taken together, these data demonstrate that both CaM-binding domains of CaD can bind simultaneously to the two hydrophobic regions of CaM.
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202
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Yuan T, Hyndman RD, Spence GD, Desmons B. Seismic velocity increase and deep-sea gas hydrate concentration above a bottom-simulating reflector on the northern Cascadia continental slope. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb00102] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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203
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Lew WY, Yasuda S, Yuan T, Hammond HK. Endotoxin-induced cardiac depression is associated with decreased cardiac dihydropyridine receptors in rabbits. J Mol Cell Cardiol 1996; 28:1367-71. [PMID: 8782078 DOI: 10.1006/jmcc.1996.0127] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Endotoxin depresses left ventricular (LV) contractility independently of alterations in loading conditions, acidosis, or hypoxia (Hung and Lew, 1993a). We evaluated if endotoxin-induced LV depression is associated with a decrease in functional L-type calcium channels, as reflected by the number of dihydropyridine receptors measured by [3H]-PN200-110 binding. New Zealand white rabbits were instrumented with sonomicrometers to measure the end-systolic pressure-volume relationship after i.v. saline (group 1, n = 6), 5 micrograms/kg endotoxin (group II, n = 6), or 10 micrograms/kg endotoxin (group III, n = 6). The end-systolic volume (ESV) measured at a matched end-systolic pressure did not change significantly over 6 h in group I (ESV changed by < 5 +/- 2% S.E.) and group II (ESV changed by < 3 +/- 2%), but increased markedly in group III (ESV increased 70 +/- 24%, P < 0.05), indicating LV systolic depression. We measured [3H]-PN200-110 binding in crude membrane homogenates from the left ventricle. There was a dose-dependent decrease in Bmax: 75 +/- 5 fmol/mg protein in group I, 62 +/- 3 fmol/mg in group II, and 56 +/- 5 fmol/mg in group III (P = 0.02 by ANOVA). Since the majority of dihydropyridine receptors are functional L-type calcium channels in rabbits (Lew et al., 1991), we conclude that a decreased number of dihydropyridine receptors contributes to endotoxin-induced LV depression.
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204
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Fabian H, Yuan T, Vogel HJ, Mantsch HH. Comparative analysis of the amino- and carboxy-terminal domains of calmodulin by Fourier transform infrared spectroscopy. EUROPEAN BIOPHYSICS JOURNAL : EBJ 1996; 24:195-201. [PMID: 8665835 DOI: 10.1007/bf00205100] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Fourier transform infrared spectra were obtained for mammalian calmodulin and two of its fragments produced by limited proteolysis with trypsin TR1C (1-77) and TR2C (78-148). Experiments were done in H2O, D2O and D2O/trifluoroethanol (TFE) mixtures. Information about secondary structure was obtained from analysis of the amide I and II bands; while characteristic absorbances for tyrosine, phenylalanine and carboxylate groups were analyzed for changes in tertiary structure. Our data indicate that the secondary and tertiary structure is preserved in the two half molecules of CaM, both in the apo- and Ca(2+)-saturated state. Addition of the structure-inducing solvent TFE causes marked changes only in the apo-TR1C domain. The maximum wavenumber for the amide I band of the two domains of CaM in D2O was markedly different (1642 cm-1 for TR1C versus 1646/1648 cm-1 for Ca2+ and apo-TR2C). This renders the amide I band for the intact protein very broad in comparison to that in other proteins and is indicative of a distribution of alpha-helices with slightly different hydrogen bonding patterns.
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205
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Aramini JM, Hiraoki T, Yazawa M, Yuan T, Zhang M, Vogel HJ. Lead-207 NMR: a novel probe for the study of calcium-binding proteins. J Biol Inorg Chem 1996. [DOI: 10.1007/s007750050021] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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206
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Zhang M, Yuan T, Aramini JM, Vogel HJ. Interaction of calmodulin with its binding domain of rat cerebellar nitric oxide synthase. A multinuclear NMR study. J Biol Chem 1995; 270:20901-7. [PMID: 7545663 DOI: 10.1074/jbc.270.36.20901] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The intercellular messenger nitric oxide is produced through the action of nitric oxide synthases, a class of enzymes that is regulated by calcium-calmodulin (CaM). In this work, the interaction of CaM with a 23-amino-acid residue synthetic peptide, encompassing the CaM-binding domain of constitutive rat cerebellar nitric oxide synthase (cNOS), was investigated by various NMR methods. Cadmium-113 NMR studies showed that binding of the cNOS peptide increased the affinity of CaM for metal ions and induced interdomain cooperativity in metal ion binding as earlier observed for complexes of CaM with myosin light chain kinase (MLCK) peptides. By using specific isotopically labeled [13C]methyl-Met and selenomethionine-substituted CaM in two-dimensional proton-detected 13C and 77Se NMR studies, we obtained evidence for the involvement of the Met residues of CaM in the binding of the cNOS peptide. These residues form two hydrophobic surface areas on CaM, and they are also involved in the binding of other target proteins. A nitroxide spin-labeled version of the cNOS peptide caused broadening only for NMR resonances in the N-terminal half of CaM, showing that the peptide binds with a C to N orientation to the N- and C-terminal domains of CaM. pH titration experiments of CaM dimethylated with [13C]formaldehyde show that Lys-75 (and Lys-148) experience a large increase in pKa upon peptide binding; this indicates an unraveling of part of the helical linker region of CaM upon cNOS peptide binding. Taken together, our data show that the cNOS and MLCK peptides bind in a closely analogous fashion to CaM.
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207
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Yuan T, Mietzner TA, Montelaro RC, Vogel HJ. Characterization of the calmodulin binding domain of SIV transmembrane glycoprotein by NMR and CD spectroscopy. Biochemistry 1995; 34:10690-6. [PMID: 7654723 DOI: 10.1021/bi00033a045] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Recent experimental evidence has shown that the C-terminal peptide of the HIV/SIV transmembrane glycoprotein 41 (gp41) can bind very tightly to calmodulin (CaM). These findings imply a potential mechanism for HIV/SIV cytopathogenesis, which involves the uncoupling of some critical cellular signal transduction pathways that are normally mediated by CaM. Here, we present circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy studies of a 28-residue synthetic peptide, SIV-L, corresponding to the C-terminal portion of the SIV transmembrane glycoprotein gp41. CD studies recorded in aqueous solution show a dramatic increase in the amount of alpha-helical structure of the SIV-L peptide upon binding to calcium-CaM. Two-dimensional NMR experiments were performed to determine the secondary structure of the peptide in 25% aqueous trifluoroethanol solution. In this alpha-helix inducing solvent, the observed nuclear Overhauser effects, as well as the alpha 1H and alpha 13C chemical shift changes, demonstrate that a continuous alpha-helix is formed from W3 to L28, although there is some distortion around P17. This result is in accordance with those obtained for many other CaM-binding peptides. Subsequent one-dimensional NMR titration experiments of calcium-CaM and the SIV-L peptide suggest that the peptide can bind to CaM with a 1:1 stoichiometry and that the peptide binding involves both the N- and C-lobe of CaM. However, gel mobility shift assays suggest that the peptide CaM interaction may be more complicated, as oligomeric forms of CaM and the SIV-L peptide were found. These studies provide a potential molecular basis for HIV/SIV cytopathogenesis.
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208
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Banka CL, Yuan T, de Beer MC, Kindy M, Curtiss LK, de Beer FC. Serum amyloid A (SAA): influence on HDL-mediated cellular cholesterol efflux. J Lipid Res 1995; 36:1058-65. [PMID: 7658153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Normal high density lipoprotein (N-HDL) is remodeled during acute phase (AP) reactions by the association of serum amyloid A (SAA) and the depletion of apolipoprotein (apo) A-I. To determine the impact of this remodeling on HDL function, the capacities of N-HDL and AP-HDL to associate with and promote cholesterol efflux from human monocytic THP-1 cells were compared. THP-1 cells preferentially bound AP-HDL compared with N-HDL. Examination of the AP-HDL particles bound to THP-1 cells revealed a disproportionate association of an apoSAA-enriched, apoA-I-depleted subpopulation compared with the composition of the starting material. However, N-HDL and AP-HDL promoted cholesterol efflux from THP-1 cells equally efficiently and in a dose-dependent manner. When N-HDL was experimentally remodeled with apoSAA to achieve an apoprotein composition similar to that of the preferentially bound particles, cellular cholesterol efflux was reduced by 30%. The remodelling of HDL with apoSAA during the acute phase reaction alters cholesterol efflux only when apoSAA constitutes more than 50% of the HDL protein.
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209
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Banka CL, Yuan T, de Beer MC, Kindy M, Curtiss LK, de Beer FC. Serum amyloid A (SAA): influence on HDL-mediated cellular cholesterol efflux. J Lipid Res 1995. [DOI: 10.1016/s0022-2275(20)39863-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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210
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de Beer MC, Yuan T, Kindy MS, Asztalos BF, Roheim PS, de Beer FC. Characterization of constitutive human serum amyloid A protein (SAA4) as an apolipoprotein. J Lipid Res 1995. [DOI: 10.1016/s0022-2275(20)39886-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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211
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de Beer MC, Yuan T, Kindy MS, Asztalos BF, Roheim PS, de Beer FC. Characterization of constitutive human serum amyloid A protein (SAA4) as an apolipoprotein. J Lipid Res 1995; 36:526-34. [PMID: 7775864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Serum amyloid A proteins (SAAs), a family of homologous molecules, are apolipoproteins of high density lipoprotein (HDL). They can be divided into two groups. The first group comprises the well-characterized acute phase SAAs that associate with HDL during inflammation, thereby remodeling the HDL particle by displacing apolipoprotein (apo)A-I. The second group consists of the recently discovered constitutive SAAs, mouse SAA5 and human SAA4. They exist as minor apolipoproteins on HDL but constitute more than 90% of the total SAA during homeostasis. We have characterized human SAA4 as an apolipoprotein. During homeostasis, SAA4 is synthesized only in the liver. Purification of SAA4 has been described and its plasma concentration has been established at 55 +/- 13 micrograms/ml in 26 healthy individuals. It was present on all HDL density classes and very low density lipoprotein (VLDL) but was absent from low density lipoprotein (LDL). Using two-dimensional electrophoresis and phosphorimaging, SAA4 was found to be associated with a specific subpopulation of only three HDL particles, not involved in the initial cholesterol transfer from cells.
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212
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Yuan T, Lien RJ, McDaniel GR. Effects of increased rearing period body weights and early photostimulation on broiler breeder egg production. Poult Sci 1994; 73:792-800. [PMID: 8072921 DOI: 10.3382/ps.0730792] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Broiler breeder pullets were subjected to photostimulation (PS) at either 14, 17, or 20 wk of age after attaining greater than recommended BW during rearing in order to determine effects on age at onset of lay, egg weight, and egg production. During rearing, feed was consumed ad libitum (AL) or provided in allotments resulting in growth to projected BW of 2.8 (heavy, HV) or 2.3 kg (light, LT) at 20 wk. Rearing period feeding and age at PS treatments made up a 3 x 3 factorial arrangement. A single restricted feeding program was provided during lay. Although age at first egg in the AL treatment was earlier than in HV and LT treatments, total production by HV and LT birds was greater because peak and postpeak production by AL birds were depressed. Relative to PS at 20 wk, PS at 14 and 17 wk advanced age at first egg and increased cumulative production to 30 wk. However, early PS decreased peak production and, therefore, did not affect total production. Mean egg weight and settable egg production (egg weight > 50 g) were increased in HV and LT treatments. Egg weight and settable egg production were not affected by age at PS. These results indicate that the onset of lay by broiler breeders can be advanced by early PS and that increased BW facilitates this. However, allowing greater BW during rearing does not compensate for reduced early egg weights and results in decreased total production and mean egg weights when feed is provided at recommended levels during lay.
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213
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Jiang H, Yuan T, How H, Widom A, Vittoria C, Chrisey D, Horwitz J, Drehman A. Measurements of surface impedance, London penetration depth, and coherence length in Y-Ba-Cu-O films at microwave frequencies. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:9924-9932. [PMID: 10009794 DOI: 10.1103/physrevb.49.9924] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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214
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Lien R, Yuan T. Effect of Delayed Light Stimulation on Egg Production by Broiler Breeder Pullets of Low Body Weight. J APPL POULTRY RES 1994. [DOI: 10.1093/japr/3.1.40] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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215
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Zhang M, Yuan T, Vogel HJ. A peptide analog of the calmodulin-binding domain of myosin light chain kinase adopts an alpha-helical structure in aqueous trifluoroethanol. Protein Sci 1993; 2:1931-7. [PMID: 8268802 PMCID: PMC2142276 DOI: 10.1002/pro.5560021114] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A 22-residue synthetic peptide encompassing the calmodulin (CaM)-binding domain of skeletal muscle myosin light chain kinase was studied by two-dimensional NMR and CD spectroscopy. In water the peptide does not form any regular structure; however, addition of the helix-inducing solvent trifluoroethanol (TFE) causes it to form an alpha-helical structure. The proton NMR spectra of this peptide in 25% and 40% TFE were assigned by double quantum-filtered J-correlated spectroscopy, total correlation spectroscopy, and nuclear Overhauser effect correlated spectroscopy spectra. In addition, the alpha-carbon chemical shifts were obtained from (1H,13C)-heteronuclear multiple quantum coherence spectra. The presence of numerous dNN(i, i + 1), d alpha N(i, i + 3), and d alpha beta(i, i + 3) NOE crosspeaks indicates that an alpha-helix can be formed from residues 3 to 20; this is further supported by the CD data. Upfield alpha-proton and downfield alpha-carbon shifts in this region of the peptide provide further support for the formation of an alpha-helix. The helix induced by TFE appears to be similar to that formed upon binding of the peptide to CaM.
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216
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Liu S, Wu T, Yang Z, Yuan T. [The isolation and identification of a Clostridium botulinum serotype A strain]. WEI SHENG WU XUE BAO = ACTA MICROBIOLOGICA SINICA 1993; 33:280-4. [PMID: 8256440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
319 soil specimens were collected from different places of China for isolating Clostridium botulinum. A strain of Clostridium botulinum was isolated from a culture of soil specimens in Ruoergai of Sichuan Province, the strain was called As-3. The As-3 was identified as Clostridium botulinum serotype A according to its biological properties, biochemical serological and toxicological characteristics and DNA determination. Its DNA G + C mol is 24.9%. The toxin produced by As-3 strain can only be neutralized by type A antiserum.
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217
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Jiang H, Widom A, Huang Y, Yuan T, Vittoria C, Chrisey DB, Horwitz JS. Quantum nucleation and thermal activation of vortex rings in high-Tc superconductors. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:3048-3053. [PMID: 10001856 DOI: 10.1103/physrevb.45.3048] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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218
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Rao VV, Yuan T. A study of socioeconomic determinants of family planning practice based on cross cultural regressions. GENUS 1980; 36:63-77. [PMID: 12264250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023] Open
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