COMPARISON OF THE NATIVE CCMV VIRION WITH IN-VITRO ASSEMBLED CCMW VIRIONS BY CRYOELECTRON MICROSCOPY AND IMAGE-RECONSTRUCTION

Cryoelectron microscopy and three-dimensional image reconstruction ana lysis has been used to determine the structure of native and in vitro assembled cowpea chlorotic mottle virus (CCMV) virions and capsids to 25-Angstrom resolution. Purified CCMV coat protein was used in conjunc tion with in vitro transcribed viral RNAs to assemble RNA 1 only, RNA 2 only, RNA 3/4 only, and empty (RNA lacking) virions. The image recon structions demonstrate that the in vitro assembled CCMV virions are mo rphologically indistinguishable from native virions purified from infe cted plants. The viral RNA (vRNA) is packaged similarly within the dif ferent types of virions. The centers of all assembled particles are ge nerally devoid of density and the vRNA packs against the interior surf ace of the virion shell. The vRNA appears to adopt an ordered conforma tion at each of the quasi-threefold axes. (C) 1998 Academic Press.