Recombinant DNA derived tobacco mosaic virus (vulgare strain) coat protein (r-TMVP) was obtained by cloning and expression in Eschericia coli and was purified by column chromatography, self-assembly ploymerization, and precipitation. SDS-PAGE, amino terminal sequencing, and immunoblotting with polyclonal antibodies raised against TMVP confirmed the identity and purity of the recombinant protein. Isoelectric focusing in 8 M urea and fast atom bombardment mass spectrometry demonstrated that the r-TMVP is not acetylated at the amino terminus, unlike the wild-type protein isolated from the tobacco plant derived virus. The characterization of r-TMVP with regard to its self-assembly properties revealed reversible endothermic polymerization as studied by analytical ultracentrifugation, circular dichroism, and electron microscopy. However, the details of the assembly process differed from those of the wild-type protein. At neutral pH, low ionic strength, and 20.degree. C, TMVP forms a 20S two-turn helical rod that acts as a nucleus for further assembly with RNA and additional TMVP to form TMV. Under more acidic conditions, this 20S structure also acts as a nucleus for protein self-assembly to form viruslike RNA-free rods. The r-TMVP that is not acetylated carries an extra positive charge at the amino terminus and does not appear to form the 20S nucleus. Instead, it forms a 28S four-layer structure, which resembles in size and structure the dimer of the bilayer disk formed by the wild-type protein at pH 8.0, high ionic strength, and 20.degree. C. However, like TMVP at pH 5-6, the recombinant coat protein forms long helical rods which, depending on the pathway of formation, may exhibit packing imperfections. In contrast to TMVP, solutions of r-TMVP helical rods also contain some unpolymerized disklike structures, which suggests either two structures for the 28S aggregates, two parallel polymerization pathways, or both. The influence of the quaternary structure due to the additional charge at the amino terminus of r-TMVP is significant even though this end of the protein chain is on the outside of the protein in the disk, the assembled rod, and the virus.