Mobility involved in protein—RNA interaction in spherical plant viruses, studied by nuclear magnetic resonance spectroscopy

Abstract

In a previous paper [I] we have shown that the protein region in cowpea chlorotic mottle virus (CCMV) involved in protein-RNA interaction is very mobile in the absence of RNA. Upon binding RNA, immobilization of this protein region occurred. From a comparison with other systems, e.g. tobacco mosaic virus [2-41, tomato bushy stunt virus [5], southern bean mosaic virus [6], histones [7] and protamines [8] and using protein secondary structure predictions [9] we have suggested a general model for the protein-RNA interaction in simple plant viruses. This model is based on a random coil to a-helix transition for the protein region, interacting with RNA upon binding. In this paper we extend our work to three other spherical plant viruses. We used brome mosaic virus (BMV), belladonna mottle virus (BdMV) and cowpea mosaic virus (CPMV) since the stability of these three viruses depends to a different extent upon protein-RNA and protein-protein interactions [lo]. The results obtained confirm our previous ideas about protein-RNA interaction in simple plant viruses and permit a further retinement of our model.