@article {2264, title = {The hand of the filamentous bacteriophage helix}, journal = {European Biophysics Journal with Biophysics Letters}, volume = {37}, number = {6}, year = {2008}, note = {ISI Document Delivery No.: 314QDTimes Cited: 1Cited Reference Count: 30Straus, S. K. Scott, W. R. P. Marvin, D. A.}, month = {Jul}, pages = {1077-1082}, type = {Article}, abstract = {Filamentous bacteriophage (Inovirus) is a widely studied model system in molecular biophysics. The structure of the virion has been analysed by various methods, but the methods have seldom questioned the hand of the virion helix. The hand of the helix relating the protein subunits in the class II virus strain Pf1 was chosen by calculating an electron-density distribution from X-ray fibre diffraction data, using a maximum-entropy method, but to our knowledge this method has not been used for a similar purpose in any other system. Moreover, this same hand was extended only by analogy, with no direct analysis of the corresponding data, to the class I virus strain Ff (fd, f1, M13), which has a different helix symmetry. Here we use published solid-state NMR data to confirm the validity of the hand of Pf1 chosen by the maximum-entropy method, and to confirm the extension to Ff.}, keywords = {ALPHA-HELIX, COAT PROTEIN, ELECTRON-DENSITY, FIBER DIFFRACTION DATA, fibre diffraction, MEMBRANE-PROTEIN, models, MOLECULAR-STRUCTURE DETERMINATION, NMR-SPECTROSCOPY, PF1, RESOLUTION, SOLID-STATE NMR, STATE, XPLOR-NIH}, isbn = {0175-7571}, url = {://000256823000038}, author = {Straus, S. K. and Scott, W. R. P. and Marvin, D. A.} } @article {1473, title = {Beads-on-a-string, characterization of Ets-1 sumoylated within its flexible N-terminal sequence}, journal = {Journal of Biological Chemistry}, volume = {281}, number = {7}, year = {2006}, note = {ISI Document Delivery No.: 011NNTimes Cited: 11Cited Reference Count: 62}, month = {Feb}, pages = {4164-4172}, type = {Article}, abstract = {Sumoylation regulates the activities of several members of the ETS transcription factor family. To provide a molecular framework for understanding this regulation, we have characterized the conjugation of Ets-1 with SUMO-1. Ets-1 is modified in vivo predominantly at a consensus sumoylation motif containing Lys-15. This lysine is located within the unstructured N-terminal segment of Ets-1 preceding its PNT domain. Using NMR spectroscopy, we demonstrate that the Ets-1 sumoylation motif associates with the substrate binding site on the SUMO-conjugating enzyme UBC9 (K-d similar to 400 mu M) and that the PNT domain is not involved in this interaction. Ets-1 with Lys-15 mutated to an arginine still binds UBC9 with an affinity similar to the wild type protein, but is no longer sumoylated. NMR chemical shift and relaxation measurements reveal that the covalent attachment of mature SUMO-1, via its flexible C-terminal Gly-97, to Lys-15 of Ets-1 does not perturb the structure or dynamic properties of either protein. Therefore sumoylated Ets-1 behaves as "beads-on-a-string" with the two proteins tethered by flexible polypeptide segments containing the isopeptide linkage. Accordingly, SUMO-1 may mediate interactions of Ets-1 with signaling or transcriptional regulatory macromolecules by acting as a structurally independent docking module, rather than through the induction of a conformational change in either protein upon their covalent linkage. We also hypothesize that the flexibility of the linking polypeptide sequence may be a general feature contributing to the recognition of SUMO-modified proteins by their downstream effectors.}, keywords = {BACKBONE DYNAMICS, CRYSTAL-STRUCTURE, DNA-BINDING, MODIFICATION, NMR-SPECTROSCOPY, NUCLEAR-BODIES, POINTED DOMAIN, SUMO, TRANSCRIPTIONAL REPRESSION, TUMOR-SUPPRESSOR, UBIQUITIN-CONJUGATING ENZYME}, isbn = {0021-9258}, url = {://000235275300048}, author = {Macauley, M. S. and Errington, W. J. and Scharpf, M. and Mackereth, C. D. and Blaszczak, A. G. and Graves, B. J. and McIntosh, L. P.} } @article {1233, title = {Variable control of Ets-1 DNA binding by multiple phosphates in an unstructured region}, journal = {Science}, volume = {309}, number = {5731}, year = {2005}, note = {ISI Document Delivery No.: 941KDTimes Cited: 66Cited Reference Count: 30}, month = {Jul}, pages = {142-145}, type = {Article}, abstract = {Cell signaling that culminates in posttranslational modifications directs protein activity. Here we report how multiple Ca2+-dependent phosphorylation sites within the transcription activator Ets-1 act additively to produce graded DNA binding affinity. Nuclear magnetic resonance spectroscopic analyses show that phosphorylation shifts Ets-1 from a dynamic conformation poised to bind DNA to a well-folded inhibited state. These phosphates lie in an unstructured flexible region that functions as the allosteric effector of autoinhibition. Variable phosphorylation thus serves as a "rheostat" for cell signaling to fine-tune transcription at the level of DNA binding.}, keywords = {allosteric regulation, AUTOINHIBITION, DOMAIN, DYNAMICS, NMR-SPECTROSCOPY, PHOSPHORYLATION, PROTEIN, SITES, TRANSACTIVATION, TRANSCRIPTION FACTOR NFAT1}, isbn = {0036-8075}, url = {://000230212800079}, author = {Pufall, M. A. and Lee, G. M. and Nelson, M. L. and Kang, H. S. and Velyvis, A. and Kay, L. E. and McIntosh, L. P. and Graves, B. J.} } @article {847, title = {Cyclic enterobacterial common antigen: Potential contaminant of bacterially expressed protein preparations}, journal = {Journal of Biomolecular Nmr}, volume = {29}, number = {2}, year = {2004}, note = {ISI Document Delivery No.: 801ZPTimes Cited: 5Cited Reference Count: 10}, month = {Jun}, pages = {199-204}, type = {Article}, abstract = {We have previously reported the identification of the cyclic enterobacterial common antigen (ECACYC) polysaccharide in E. coli strains commonly used for heterologous protein expression (PJA Erbel et al., J. Bacteriol. 185 ( 2003): 1995). Following this initial report, interactions among several NMR groups established that characteristic N-acetyl signals of ECACYC have been observed in N-15-H-1 HSQC spectra of samples of various bacterially-expressed proteins suggesting that this water-soluble carbohydrate is a common contaminant. We provide NMR spectroscopic tools to recognize ECACYC in protein samples, as well as several methods to remove this contaminant. Early recognition of ECA-based NMR signals will prevent time-consuming analyses of this copurifying carbohydrate.}, keywords = {enterobacterial common antigen, ESCHERICHIA-COLI, heterologous protein expression, IDENTIFICATION, N-acetylated carbohydrate, NMR-SPECTROSCOPY, protein purification}, isbn = {0925-2738}, url = {://000220134100007}, author = {Erbel, P. J. A. and Seidel, R. and Macintosh, S. E. and Gentile, L. N. and Amor, J. C. and Kahn, R. A. and Prestegard, J. H. and McIntosh, L. P. and Gardner, K. H.} } @article {993, title = {Recent developments in solid-state magic-angle spinning, nuclear magnetic resonance of fully and significantly isotopically labelled peptides and proteins}, journal = {Philosophical Transactions of the Royal Society of London Series B-Biological Sciences}, volume = {359}, number = {1446}, year = {2004}, note = {ISI Document Delivery No.: 834XSTimes Cited: 7Cited Reference Count: 125}, month = {Jun}, pages = {997-1008}, type = {Review}, abstract = {In recent years, a large number of solid-state nuclear magnetic resonance (NMR) techniques have been developed and applied to the study of fully or significantly isotopically labelled (C-13, N-15 or C-13/N-15) biomolecules. In the past few years, the first structures of C-13/N-15-labelled peptides, Gly-Ile and Met-Leu-Phe, and a protein, Src-homology 3 domain, were solved using magic-angle spinning NMR, without recourse to any structural information obtained from other methods. This progress has been made possible by the development of NMR experiments to assign solid-state spectra and experiments to extract distance and orientational information. Another key aspect to the success of solid-state NMR is the advances made in sample preparation. These improvements will be reviewed in this contribution. Future prospects for the application of solid-state NMR to interesting biological questions will also briefly be discussed.}, keywords = {assignment strategies, CHEMICAL-SHIFT ANISOTROPIES, CROSS-POLARIZATION, DIPOLAR-CORRELATION SPECTROSCOPY, DISTANCE, HIGH-FIELD, magic-angle spinning, MAS NMR, MEASUREMENTS, MEMBRANE-PROTEIN, NMR-SPECTROSCOPY, peptide and protein labelling, RESOLUTION, ROTATING SOLIDS, SH3 DOMAIN, SOLID-STATE NMR, SPECTRIN, structural parameters}, isbn = {0962-8436}, url = {://000222444800010}, author = {Straus, S. K.} } @article {891, title = {Structural basis of actin sequestration by thymosin-beta 4: implications for WH2 proteins}, journal = {Embo Journal}, volume = {23}, number = {18}, year = {2004}, note = {ISI Document Delivery No.: 861IFTimes Cited: 48Cited Reference Count: 51}, month = {Sep}, pages = {3599-3608}, type = {Article}, abstract = {The WH2 (Wiscott - Aldridge syndrome protein homology domain 2) repeat is an actin interacting motif found in monomer sequestering and filament assembly proteins. We have stabilized the prototypical WH2 family member, thymosin-beta4 (Tbeta4), with respect to actin, by creating a hybrid between gelsolin domain 1 and the C-terminal half of Tbeta4 (G1-Tbeta4). This hybrid protein sequesters actin monomers, severs actin filaments and acts as a leaky barbed end cap. Here, we present the structure of the G1-Tbeta4: actin complex at 2Angstrom resolution. The structure reveals that Tbeta4 sequesters by capping both ends of the actin monomer, and that exchange of actin between Tb4 and profilin is mediated by a minor overlap in binding sites. The structure implies that multiple WH2 motif-containing proteins will associate longitudinally with actin filaments. Finally, we discuss the role of the WH2 motif in arp2/3 activation.}, keywords = {actin, ARP2/3 COMPLEX, BETA-THYMOSINS, BINDING-PROTEINS, CRYSTAL-STRUCTURE, DNASE-I, F-ACTIN, MONOMERIC, NEGATIVE COOPERATIVITY, NMR-SPECTROSCOPY, NUCLEAR-MAGNETIC-RESONANCE, protein crystallography, SCAR, VCA, WASp, WH2}, isbn = {0261-4189}, url = {://000224409100003}, author = {Irobi, E. and Aguda, A. H. and Larsson, M. and Guerin, C. and Yin, H. L. and Burtnick, L. D. and Blanchoin, L. and Robinson, R. C.} } @article {444, title = {Carbohydrate-binding modules recognize fine substructures of cellulose}, journal = {Journal of Biological Chemistry}, volume = {277}, number = {52}, year = {2002}, note = {ISI Document Delivery No.: 631QDTimes Cited: 20Cited Reference Count: 36}, month = {Dec}, pages = {50245-50254}, type = {Article}, abstract = {Competition isotherms are used to identify the set of cellulose substructures to which cellulose binding modules (CBMs) from families 2a, 3, 4, 9, and 17 bind. The experiments are based on coupling a unique fluorescent tag to each CBM in a manner that does not alter the natural binding properties of the CBM and therefore allows the surface and solution concentrations of each CBM to be monitored as a function of time and composition. Adsorption and surface exchange of like or competing CBMs are monitored using a range of cellulose preparations varying in both crystallinity and provenance. CBMs from families 2a, 3,4,9, and 17 are shown to recognize different physical forms of prepared cellulose. The demonstration of the very fine binding specificity of cellulose-specific CBMs implies that the polysaccharide targets of CBMs extend down to the resolution of cellulose microstructures.}, keywords = {BACTERIAL, CELLULASE, CRYSTALLINE CELLULOSE, DOMAIN, EXOGLUCANASE, FIMI CENC, NMR-SPECTROSCOPY, PROTEIN-A, SPECIFICITY, TRYPTOPHAN RESIDUES, XYLANASE 10A}, isbn = {0021-9258}, url = {://000180177700007}, author = {McLean, B. W. and Boraston, A. B. and Brouwer, D. and Sanaie, N. and Fyfe, C. A. and Warren, R. A. J. and Kilburn, D. G. and Haynes, C. A.} } @article {4548, title = {One-electron oxidation of paramagnetic chromium(II) alkyl complexes with alkyl halides: synthesis and structure of five-coordinate chromium(III) complexes}, journal = {Journal of the Chemical Society-Dalton Transactions}, number = {2}, year = {1999}, note = {ISI Document Delivery No.: 162JPTimes Cited: 18Cited Reference Count: 69}, month = {Jan}, pages = {147-154}, type = {Article}, abstract = {The reaction of square-planar, high-spin CrR[N(SiMe2CH2PPh2)(2)] (R = Me, CH2SiMe3) with alkyl halides (MeI, CF3CH2I, MeBr, PhCH2Cl) generates one-electron oxidation products Cr(R)X[N(SiMe2CH2PPh2)(2)], unusual examples of five-coordinate chromium(III) complexes. Cr(Me)Br[N(SiMe2CH2PPh2)(2)] and Cr(CH2SiMe3)Cl[N(SiMe2CH2PPh2)(2)] have structurally characterized. Alkylation of the latter complex with LiCH2SiMe3 gave a five-coordinate Cr(III) dialkyl complex Cr(CH2SiMe3)(2)[N(SiMe2CH2PPh2)(2)](2), which was structurally characterized as well. Attempts to isolate sterically unencumbered Cr(III) dialkyl (e.g., dimethyl) complexes resulted in decomposition. Addition of an excess of PhCH2Cl to {[(Ph2PCH2SiMe2)(2)N]Cr}(2)(mu-Cl)(2) resulted in halide-transfer to form CrCl2(TNF)[N(SiMe2CH2PPh2)(2)] in low yield. Reaction of the low-spin CrCp[N(SiMe2CH2PPh2)(2)] complex with PhCH2Cl, however, gave both Cr(Cp)(CH2Ph)[N(SiMe2CH2PPh2)(2)] and Cr(CP)Cl[N(SiMe2CH2CH2PPh2)(2)]. The five five-coordinate Cr(III) alkyl halide complexes do not polymerize ethylene at 60 degrees C and 1 atm; the dialkyl complex Cr(CH2SiMe3)(2)[N(SiMe2CH2PPh2)(2)] does catalyze polyethylene formation but is quickly deactivated. A discussion comparing the structural distortions observed in these five-coordinate high-spin d(3) Cr(III) complexes with those observed in the analogous low-spin d(6) Ir(III) complexes is presented.}, keywords = {17-ELECTRON, 5-COORDINATE, ATOM TRANSFER-REACTIONS, CHEMISTRY, CRYSTAL-STRUCTURE, D6 ML5 COMPLEXES, NMR-SPECTROSCOPY, ORGANIC HALIDES, POLYMERIZATION, REACTIVITY}, isbn = {0300-9246}, url = {://000078342700010}, author = {Fryzuk,Michael D. and Leznoff, D. B. and Rettig, S. J. and Young, V. G.} } @article {4235, title = {Characterization of a buried neutral histidine in Bacillus circulans xylanase: Internal dynamics and interaction with a bound water molecule}, journal = {Biochemistry}, volume = {37}, number = {7}, year = {1998}, note = {ISI Document Delivery No.: YZ886Times Cited: 13Cited Reference Count: 59}, month = {Feb}, pages = {1810-1818}, type = {Article}, abstract = {NMR spectroscopy was used to characterize the dynamic behavior of His149 in Bacillus circulans xylanase (BCX) and its interaction with an internal water molecule. Rate constants for the specific acid-and base-catalyzed exchange following bimolecular kinetics (EX2) of the nitrogen-bonded H-epsilon 2 of this buried, neutral histidine were determined, At pD(min) 7.0 and 30 degrees C, the lifetime for this proton is 9.9 h, corresponding to a protection factor of similar to 10(7) relative to that predicted for an exposed histidine, The apparent activation energies measured for specific acid and base catalysis (7.0 and 17.4 kcal/mol) indicate that exchange occurs via local structural fluctuations. Consistent with its buried environment, the N-epsilon 2-H bond vector of His149 shows restricted mobility, as evidenced by an order parameter S-2 = 0.83 determined from N-15 relaxation measurements, The crystal structure of BCX reveals that a conserved, buried water hydrogen-bonds to the H-epsilon 2 of His149. Strong support for this interaction in solution is provided by the observation of a negative nuclear Overhauser effect (NOE) and positive rotating-frame Overhauser effect (ROE) between His149 H-epsilon 2 and a water molecule with the same chemical shift as the bulk solvent. However, the chemical shift of H-epsilon 2 (12.2 ppm) and a D/H fractionation factor close to unity (0.89 +/- 0.02) indicate that this is nor a so-called low-barrier hydrogen bond. Lower and upper bounds on the lifetime of the internal water are estimated to be 10(-8) and 10(-3) s. Therefore the chemical exchange of solvent protons with those of His149 H-epsilon 2 and the diffusion or physical exchange of the internal water to which the histidine is hydrogen-bonded differ in rate by over 7 orders of magnitude.}, keywords = {ACTIVE-SITE, AMIDE PROTON-EXCHANGE, ASSIGNMENTS, DOMAIN, HYDROGEN-BOND, NMR-SPECTROSCOPY, NUCLEAR MAGNETIC-RESONANCE, PROTEINS, relaxation, TRICHODERMA-REESEI}, isbn = {0006-2960}, url = {://000072304200010}, author = {Connelly, G. P. and McIntosh, L. P.} } @article {4314, title = {Equilibrium unfolding of proteins monitored by electrospray ionization mass spectrometry: Distinguishing two-state from multi-state transitions}, journal = {Rapid Communications in Mass Spectrometry}, volume = {12}, number = {8}, year = {1998}, note = {ISI Document Delivery No.: ZJ143Times Cited: 79Cited Reference Count: 59}, pages = {435-442}, type = {Article}, abstract = {The acetic acid-induced unfolding of cytochrome c (cyt c) and apomyoglobin (aMb) are studied under equilibrium conditions by electrospray ionization (ESI) mass spectrometry (MS), The folding states of the proteins in solution are monitored by the charge state distributions that they produce during ESI, A tightly folded protein shows lower charge states than the same protein in an unfolded conformation. The ESI-MS data presented in this study show that during the denaturation of cyt c, only two distinct charge state distributions are observed. These can be attributed to the native and to the acid-unfolded conformation, respectively. In the transition region where the folded and the unfolded conformation are both present in solution, these two distributions are observed simultaneously, thus giving rise to a bimodal ESI mass spectrum. These data reflect a highly cooperative (two state) folding behavior. In contrast, the acid-induced unfolding of aMb is accompanied by gradual shifts in the maxima of the observed charge state distribution. This indicates a non cooperative unfolding behavior involving multiple protein conformations. The observations made here suggest that ESI-MS might be a general method for assessing the cooperativity of protein unfolding transitions. This study also addresses the issue of {\textquoteright}secondary{\textquoteright} solvent effects for ESI-MS studies on the acid-induced unfolding of proteins. These effects influence the ESI charge state distribution without being related to conformational changes of the protein in solution and could potentially complicate the interpretation of ESI mass spectra, Data obtained for bovine pancreatic trypsin inhibitor and ubiquitin indicate that secondary solvent effects influence the observed charge state distributions only to a very minor extent between pH 8.5 and 2.5. (C) 1998 John Wiley \& Sons, Ltd.}, keywords = {CONFORMATIONAL-CHANGES, CYTOCHROME-C, FERRICYTOCHROME-C, FOLDING, HYDROGEN-DEUTERIUM EXCHANGE, INTERMEDIATE, MOLECULAR-BASIS, MOLTEN GLOBULE, NMR-SPECTROSCOPY, POSITIVE-ION, STRUCTURAL CHARACTERIZATION}, isbn = {0951-4198}, url = {://000073183800005}, author = {Konermann, L. and Douglas, D. J.} } @article {3707, title = {Structure of the N-terminal cellulose-binding domain of Cellulomonas fimi CenC determined by nuclear magnetic resonance spectroscopy}, journal = {Biochemistry}, volume = {35}, number = {45}, year = {1996}, note = {ISI Document Delivery No.: VT081Times Cited: 94Cited Reference Count: 90}, month = {Nov}, pages = {14381-14394}, type = {Article}, abstract = {Multidimensional heteronuclear nuclear magnetic resonance (NMR) spectroscopy was used to determine the tertiary structure of the 152 amino acid N-terminal cellulose-binding domain from Cellulomonas fimi 1,4-beta-glucanase CenC (CBDN1) CBDN1 was studied in the presence of saturating concentrations of cellotetraose, but due to spectral overlap, the oligosaccharide was not included in the structure calculations. A total of 1705 interproton nuclear Overhauser effect (NOE), 56 phi, 88 psi, 42 chi 1, 9 chi 2 dihedral angle, and 88 hydrogen-bond restraints were used to calculate 25 final structures. These structures have a rmsd from the average of 0.79 +/- 0.11 Angstrom for all backbone atoms excluding disordered termini and 0.44 +/- 0.05 Angstrom for residues with regular secondary structures. CBDN1 is composed of 10 beta-strands, folded into two antiparallel beta-sheets with the topology of a jelly-roll beta-sandwich. The strands forming the face of the protein previously determined by chemical shift perturbations to be responsible for cellooligosaccharide binding [Johnson, P. E., Tomme, P., Joshi, M. D., \& McIntosh, L. P. (1996) Biochemistry, 35, 13895-13906] are shorter than those forming the opposite side of the protein. This results in a 5-stranded binding cleft, containing a central strip of hydrophobic residues that is flanked on both sides by polar hydrogen-bonding groups. The presence of this cleft provides a structural explanation for the unique selectivity of CBDN1 for amorphous cellulose and other soluble oligosaccharides and the lack of binding to crystalline cellulose, The tertiary structure of CBDN1 is strikingly similar to that of the bacterial 1,3-1,4-beta-glucanases, as well as other sugar-binding proteins with jelly-roll folds.}, keywords = {3-DIMENSIONAL SOLUTION STRUCTURE, C-13-ENRICHED PROTEINS, CHEMICAL-SHIFT, DISTANCE GEOMETRY, INDEX, ISOTOPICALLY-ENRICHED PROTEINS, LARGER PROTEINS, NMR-SPECTROSCOPY, REESEI CELLOBIOHYDROLASE-I, SIDE-CHAIN RESONANCES, TRICHODERMA-REESEI}, isbn = {0006-2960}, url = {://A1996VT08100039}, author = {Johnson, P. E. and Joshi, M. D. and Tomme, P. and Kilburn, D. G. and McIntosh, L. P.} } @article {7186, title = {CONTIGNASTEROL, A HIGHLY OXYGENATED STEROID WITH THE UNNATURAL 14-BETA CONFIGURATION FROM THE MARINE SPONGE PETROSIA-CONTIGNATA THIELE, 1899}, journal = {Journal of Organic Chemistry}, volume = {57}, number = {2}, year = {1992}, note = {ISI Document Delivery No.: HA466Times Cited: 56Cited Reference Count: 18}, month = {Jan}, pages = {525-528}, type = {Article}, abstract = {Contignasterol (1), a highly oxygenated steroid with the {\textquoteright}{\textquoteright}unnatural{\textquoteright}{\textquoteright} 14-beta proton configuration and a cyclic hemiacetal functionality in its side chain, has been isolated from the marine sponge Petrosia contignata. The structure of contignasterol was elucidated via spectroscopic studies of its tetraacetate 2 and its reduction product pentaacetate 5. Contignasterol (1) is the first example of a naturally occurring steroid with the {\textquoteright}{\textquoteright}unnatural{\textquoteright}{\textquoteright} 14-beta proton configuration.}, keywords = {C-13 ASSIGNMENTS, H-1, NMR-SPECTROSCOPY}, isbn = {0022-3263}, url = {://A1992HA46600024}, author = {Burgoyne, D. L. and Andersen, R. J. and Allen, T. M.} }