The structure of alfalfa mosaic virus capsid protein assembled as a T=1 icosahedral particle at 4.0-A resolution

Abstract

reported the structure of alfalfa mosaic virus assembled from the capsid protein as a T‫1؍‬ icosahedral empty particle at 4.5-Å resolution. The information contained in the structure included the particle size, protein shell thickness, presence of wide holes at the icosahedral fivefold axes, and a proposal that the capsid protein adopts a ␤-barrel structure. In the present work, the X-ray diffraction data of Fukuyama et al. as well as the data subsequently collected by I. Fita, Y. Hata, and M. G. Rossmann (unpublished) were reprocessed to 4.0-Å resolution, and the structure was solved by molecular replacement. The current structure allowed the tracing of the polypeptide chain of the capsid protein confirming the ␤-sandwich fold and provides information on intersubunit interactions in the particle. However, it was not possible to definitively assign the amino acid sequence to the side chain density at 4-Å resolution. The particle structure was also determined by cryoelectron microscopy and image reconstruction methods and found to be in excellent agreement with the X-ray model.

A Plant-Produced Pfs25 VLP Malaria Vaccine Candidate Induces Persistent Transmission Blocking Antibodies against Plasmodium falciparum in Immunized Mice

“…Purified Pfs25-CP VLPs were shown to be highly consistent in size with an estimated 20–30% incorporation of Pfs25 onto the VLP surface. Cleavage between Pfs25 and CP is believed to be necessary for the formation of the T = 1 icosahedral particles observed with Pfs25-CP VLPs, as well as by the demonstrated lack of assembled VLPs in the absence of cleavage [51] , [52] (FhCMB, unpublished observations).…”

Atomic force microscopy investigation of Mason–Pfizer monkey virus and human immunodeficiency virus type 1 reassembled particles

“…Bacteriophage HK97, for example, passes through a series of structural states as maturation cleavages in the capsid protein occur (Wikoff et al, 2006), and in other bacteriophages, scaffolding proteins mediate structural transitions (Galisteo and King, 1993). Even in simple icosahedral plant viruses, major rearrangements are known, as for example the conversion of brome mosaic virus, and alfalfa mosaic virus T = 3 virions into T = 1 particles upon cleavage of the coat protein (Kumar et al, 1997;Larson et al, 2005).…”

The Structure of Elongated Viral Capsids

“…The number of protein subunits in the in vitro reconstituted capsids have been determined from their molecular weights and correspond to N sub ¼ 60, 132, 150, 186, and 240 (34). Only the smallest capsid has been reconstructed by x-ray (38) and is a spherical T ¼ 1 composed of 12 pentamers. The elongated particles have a diameter similar to that of the icosahedral one, hence they should have T end ¼ 1 caps.…”