CHARACTERIZATION OF THE BROME MOSAIC-VIRUS MOVEMENT PROTEIN EXPRESSEDIN ESCHERICHIA-COLI

The biochemical and functional properties of the movement protein (MP) of brome mosaic virus (BMV) were investigated. Expression and purific ation of the BMV MP from Escherichia coli resulted in a pure and solub le protein preparation. Sucrose gradient centrifugation revealed that BMV MP forms oligomers consisting of two or more copies but no higher order multimers even when different ionic strengths and pHs were appli ed. Nitro-cellulose filter binding and gel retardation studies showed that in vitro the BMV MP preferentially bound to ss nucleic acids (RNA and DNA); the affinity to ssRNA was lower compared to BMV coat protei n. The binding to ss nucleic acid was cooperative and not sequence spe cific and the hypothetical binding site was calculated to be around th ree to six nucleotides per MP monomer. The nucleic acid binding proper ties of the BMV MP are discussed in relation to the recent finding tha t this protein is also able to form tubular structures in infected pro toplasts. (C) 1998 Academic Press.