Browsing by Author "Davis, Robert"
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Item The Influence of N-Linked Glycans on the MolecularDynamics of the HIV-1 gp120 V3 Loop(PLoS ONE, 2013) Wood, Natasha T.; Fadda, Elisa; Davis, Robert; Grant, Oliver C.; Martin, Joanne C.; Woods, Robert J.; Travers, Simon A.N-linked glycans attached to specific amino acids of the gp120 envelope trimer of a HIV virion can modulate the binding affinity of gp120 to CD4, influence coreceptor tropism, and play an important role in neutralising antibody responses. Because of the challenges associated with crystallising fully glycosylated proteins, most structural investigations have focused on describing the features of a non-glycosylated HIV-1 gp120 protein. Here, we use a computational approach to determine the influence of N-linked glycans on the dynamics of the HIV-1 gp120 protein and, in particular, the V3 loop. We compare the conformational dynamics of a non-glycosylated gp120 structure to that of two glycosylated gp120 structures, one with a single, and a second with five, covalently linked high-mannose glycans. Our findings provide a clear illustration of the significant effect that N-linked glycosylation has on the temporal and spatial properties of the underlying protein structure. We find that glycans surrounding the V3 loop modulate its dynamics, conferring to the loop a marked propensity towards a more narrow conformation relative to its non-glycosylated counterpart. The conformational effect on the V3 loop provides further support for the suggestion that N-linked glycosylation plays a role in determining HIV-1 coreceptor tropism.Item The Q/U imaging experiment instrument(The American Astronomical Society, 2013) Biscoff, C.; Brizius, A.; Zwart, J.; Buder, I.; Chinone, Y.; Cleary, K.; Dumoulin, R.N.; Kusaka, A.; Monsalve, R.; Naess, S.K.; Newburgh, L.B.; Nixon, G.; Reeves, R.; Smith, K.M.; Vanderlinde, K.; Wehus, I.K.; Bogdan, M.; Bustos, R.; Church, S.E.; Davis, Robert; Dickenson, C.; Eriksen, H.K.; Gaier, T.; Gundersen, J.O.; Hasegawa, M.; Hazumi, M.; Holler, C.; Huffenberger, K.M.; Imbriale, W.A.; Ishidoshiro, K.; Jones, M.E.; Kangaslahti, P.; Kapner, D.J.; Lawrence, C.R.; Leitch, E.M.; Limon, M.; McMahon, J.J.; Miller, A.D.; Nagai, M.; Nguyen, H.; Pearson, T.J.; Piccirillo, L.; Radford, S.J.E.; Readhead, A.C.S.; Richards, J.L.; Samtleben, D.; Seiffert, M.; Shepherd, M.C.; Staggs, S.T.; Tajima, O.; Thompson, K.L.; Williamson, R.; Winstein, B.; Wollack, E.J.The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the cosmic microwave background, targeting the imprint of inflationary gravitational waves at large angular scales(∼1◦). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4m side-fed Dragonian telescope. The polarimeters that form the focal planes use a compact design based on high electron mobility transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 μKs1/2) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter array has a sensitivity of 87 μKs1/2 at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0.01. The two arrays together cover multipoles in the range ∼ 25–975. These are the largest HEMT-based arrays deployed to date. This article describes the design, calibration, performance, and sources of systematic error of the instrument.