Functional oligomerization of purified human papillomavirus types 16 and 6b E7 proteins expressed in Escherichia coli

Purified non-fused soluble human papillomavirus type 16 and 6b E7 proteins expressed in Escherichia coli were found to form oligomers. For both proteins, several degrees of oligomerization were demonstrated by gel filtration, dynamic laser light scattering and scanning electron microscopy. Oligomerization was dependent on the concentration of E7 protein. Oligomerized E7 proteins were able to bind the retinoblastoma gene product pRB and stimulated DNA synthesis when introduced into cells.