ABSTRACT
Many insect viruses survive for long periods by occlusion within robust crystalline polyhedra composed primarily of a single polyhedrin protein. We show that two different virus families form polyhedra which, despite lack of sequence similarity in the virally encoded polyhedrin protein, have identical cell constants and a body-centered cubic lattice. It is almost inconceivable that this could have arisen by chance, suggesting that the crystal lattice has been preserved because it is particularly well-suited to its function of packaging and protecting viruses.
Subject(s)
Inclusion Bodies, Viral/chemistry , Insect Viruses/chemistry , Intranuclear Inclusion Bodies/chemistry , Powder Diffraction , Viral Structural Proteins/chemistry , Animals , Cell Line , Inclusion Bodies, Viral/metabolism , Insect Viruses/physiology , Intranuclear Inclusion Bodies/metabolism , Moths/chemistry , Moths/virology , Powder Diffraction/methods , Viral Structural Proteins/metabolismABSTRACT
A holographic approach to the analysis of a Bragg scattering pattern has been described by Szöke [Acta Cryst. (1993), A49, 853-866]. The combination of crystallographic procedures and holographic interpretation allows reconstruction of an unknown part of the crystalline structure model-free if the other part of the structure is known. By introducing the concept of an average crystal, this approach is extended to point defect structures in inorganic crystals. In this case, the host lattice is well known while the defect structure is regarded as the unknown part. To demonstrate the feasibility of this approach, an Sc(2)O(3) sample doped with Er at low concentration has been studied. An additional electron density has been observed, which can be interpreted as an interstitial Er position.