TOWARDS THE STRUCTURE OF HEMAGGLUTININ-NEURAMINIDASE FROM NEWCASTLE DISEASE VIRUS. S.J. Crennell, A. Portner,+ T. Takimoto,+ W.G. Laver[[daggerdbl]] and G.L. Taylor, School of Biology and Biochemistry, University of Bath, BA1 7RH, U.K., +St Judes Childrens Research Hospital, Memphis, TN, USA. [[daggerdbl]]Australian National University, Canberra, Australia.
Hemagglutinin-Neuraminidase, (HN), one of the two surface proteins of paramyxoviruses, mediates the attachment of the virus to host cells and as such is a candidate for drug design not only against Newcastle disease (NDV), but also mumps and parainfluenza1 whose HN share 33 and 25% sequence identity respectively with NDV HN.
HN was crystallised by the hanging drop method from 0.1M acetate buffer pH4.6, 0.2M(NH4)2SO4 and 25%PEG4K. Native X-ray data were collected both on the inhouse Siemens and on beamline X11 of the DESY synchrotron, Hamburg, to 2.7Å resolution. No HN structure has been determined, although there is a predicted2 structural similarity to influenza neuraminidase which shares 17% sequence identity. Molecular replacement using the structures of influenza neuraminidase A or B, the known bacterial neuraminidases or models based on these has been unsuccessful.
Heavy atom soaks under the crystallisation buffer conditions have not yielded an isomorphous derivative. To increase side chain reactivity the crystals were transferred to MES buffer at pH6 but soaking under these conditions in the presence or absence of (NH4)2SO4 have been similarly unsuccessful. The current buffer, 30%PEG4K, 10mM Tris pH7, has at least induced reproducibility in cell dimensions between crystals. Good derivatives are still elusive, the most promising having a phasing power of 1.3 to 6Å resolution.
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2. P.M.Colman, P.A.Hoyne, M.C.Lawrence, J. Virology, 67, 2972, (1993).