Crystal structural analysis of tobacco necrosis virus at 5 A resolution

X-ray diffraction intensities for tobacco necrosis virus crystals were collected at 5 A resolution using a Weissenberg camera with a large cassette of radius 430 mm. The synchrotron radiation source at the Photon Factory was used. The crystal structure of the virus was obtained by 91 cycles of the non-crystallographic symmetry averaging. Secondary structures such as alpha-helices and beta-structures were clearly identified in the electron-density map at 5 A resolution. This virus resembles southern bean mosaic virus both in orientation of coat protein subunits and in their folding. Ordered and disordered parts of each subunit of tobacco necrosis virus are shorter and longer than the corresponding parts of the southern bean mosaic virus by 12 and 27 residues, respectively.