@article {1484, title = {Molecular structure of fd (f1, M13) filamentous bacteriophage refined with respect to X-ray fibre diffraction and solid-state NMR data supports specific models of phage assembly at the bacterial membrane}, journal = {Journal of Molecular Biology}, volume = {355}, number = {2}, year = {2006}, note = {ISI Document Delivery No.: 999EPTimes Cited: 30Cited Reference Count: 84}, month = {Jan}, pages = {294-309}, type = {Article}, abstract = {Filamentous bacteriophage (Inovirus) is a simple and well-characterized model system. The phage particle, or virion, is about 60 A in diameter and several thousand angstrom units long. The virions are assembled at the bacterial membrane as they extrude out of the host without killing it, an example of specific transport of nucleoprotein assemblages across membranes. The Ff group (fd, f1. and M13) has been especially widely studied. Models of virion assembly have been proposed based on a molecular model of the fd virion derived by X-ray fibre diffraction. A somewhat different model of the fd virion using solid-state NMR data has been proposed, not consistent with these models of assembly nor with the X-ray diffraction data. Here we show that reinterpreted NMR data are also consistent with the model derived from X-ray fibre diffraction studies, and discuss models of virion assembly. (c) 2005 Elsevier Ltd. All rights reserved.}, keywords = {ALPHA-HELICES, ALPHA-HELIX, ATOMIC REFINEMENT, fibre diffraction, filamentous bacteriophage, INOVIRUS, MAJOR COAT PROTEIN, MEMBRANE, ORIENTATIONAL RESTRAINTS, PF1 BACTERIOPHAGE, PISEMA, PROTEINS, RESOLUTION, SINGLE-STRANDED-DNA, VIRION, VIRUS}, isbn = {0022-2836}, url = {://000234371900012}, author = {Marvin, D. A. and Welsh, L. C. and Symmons, M. F. and Scott, W. R. P. and Straus, S. K.} } @article {1063, title = {Can PISEMA experiments be used to extract structural parameters for mobile beta-barrels?}, journal = {Journal of Biomolecular Nmr}, volume = {32}, number = {2}, year = {2005}, note = {ISI Document Delivery No.: 948CRTimes Cited: 4Cited Reference Count: 42}, month = {Jun}, pages = {101-111}, type = {Article}, abstract = {The effect of mobility on N-15 chemical shift/N-15-H-1 dipolar coupling (PISEMA) solid state NMR experiments applied to macroscopically oriented beta-barrels is assessed using molecular dynamics simulation data of the NalP autotransporter domain embedded in a DMPC bilayer. In agreement with previous findings for alpha-helices, the fast librational motion of the peptide planes is found to have a considerable effect on the calculated PISEMA spectra. In addition, the dependence of the chemical shift anisotropy (CSA) and dipolar coupling parameters on the calculated spectra is evaluated specifically for the beta-barrel case. It is found that the precise choice of the value of the CSA parameters sigma(11), sigma(22) and sigma(33) has only a minor effect, whereas the choice of the CSA parameter theta shifts the position of the peaks by up to 20 ppm and changes the overall shape of the spectrum significantly. As was found for alpha-helices, the choice of the NH bond distance has a large effect on the dipolar coupling constant used for the calculations. Overall, it is found that the alternating beta-strands in the barrel occupy distinct regions of the PISEMA spectra, forming patterns which may prove useful in peak assignment.}, keywords = {ANGLE-SPINNING NMR, ASSIGNMENT, COAT PROTEIN, CONSTRAINTS, DOMAIN, HELICAL WHEELS, MEMBRANE-PROTEINS, mobility of membrane beta-barrels, MOLECULAR-DYNAMICS SIMULATIONS, mosaic spread, PISEMA, SOLID-STATE NMR, SPECTROSCOPY, time averaging}, isbn = {0925-2738}, url = {://000230694100001}, author = {Bleile, D. W. and Scott, W. R. P. and Straus, S. K.} } @article {744, title = {Assessing the effects of time and spatial averaging in N-15 chemical shift/N-15-H-1 dipolar correlation solid state NMR experiments}, journal = {Journal of Biomolecular Nmr}, volume = {26}, number = {4}, year = {2003}, note = {ISI Document Delivery No.: 686MATimes Cited: 30Cited Reference Count: 51}, month = {Aug}, pages = {283-295}, type = {Article}, abstract = {The effect of time and spatial averaging on N-15 chemical shift/H-1-N-15 dipolar correlation spectra, i.e., PISEMA spectra, of alpha-helical membrane peptides and proteins is investigated. Three types of motion are considered: (a) Librational motion of the peptide planes in the alpha-helix; (b) rotation of the helix about its long axis; and (c) wobble of the helix about a nominal tilt angle. A 2ns molecular dynamics simulation of helix D of bacteriorhodopsin is used to determine the effect of librational motion on the spectral parameters. For the time averaging, the rotation and wobble of this same helix are modelled by assuming either Gaussian motion about the respective angles or a uniform distribution of a given width. For the spatial averaging, regions of possible N-15 chemical shift/H-1-N-15 dipolar splittings are computed for a distribution of rotations and/or tilt angles of the helix. The computed spectra show that under certain motional modes the N-15 chemical shift/H-1-N-15 dipolar pairs for each of the residues do not form patterns which mimic helical wheel patterns. As a result, the unambiguous identification of helix tilt and helix rotation without any resonance assignments or on the basis of a single assignment may be difficult.}, keywords = {averaging, COAT PROTEIN, GRAMICIDIN CHANNEL, ION-CHANNEL, LIPID BILAYERS, MEMBRANE-PROTEIN STRUCTURE, mobility of membrane helices, MOLECULAR-DYNAMICS SIMULATION, mosaic spread, NUCLEAR-MAGNETIC-RESONANCE, PHOSPHOLIPID-BILAYER, PISA wheels, PISEMA, SPIN-EXCHANGE, time, TRANSMEMBRANE DOMAIN}, isbn = {0925-2738}, url = {://000183324500001}, author = {Straus, S. K. and Scott, W. R. P. and Watts, A.} }