Effect of Escherichia coli chaperonin GroELS on heterologously expressed human immunodeficiency virus type 1 reverse transcriptase in vivo and in vitro

The two subunits of human immunodeficiency virus type 1 (HIV-1) reverse tra nscriptase (HIV-1 RT), p66 and p51, were coexpressed in Escherichia coli al ong with the E. coli chaperonin system GroEL/GroES. Coexpression increases the yield of heterodimeric HIV-1 RT by a factor of 4 to 5 and improves the nucleic acid binding affinity of HIV-1 RT by a factor of 1.6. We have analy zed the reasons for the improvements. The total increase in yield of HIV-1 RT can be attributed to an accumulation of RT subunits in the cells (factor of about 2.8) and an increased growth of the E. coli cells (factor of abou t 1.4). One reason for the accumulation in the cells is an improved stabili ty of HIV-1 RT subunits toward bacterial proteases. In vitro studies showed that the nucleic acid binding affinity of HIV-1 RT purified from cells tha t did not coexpress GroELS was stimulated by adding purified GroELS (approx 1.5-fold), whereas HIV-1 RT stemming from cells coexpressing GroELS was st imulated only marginally (approx 1.1-fold). The in vivo as well as the in v itro studies suggest that the chaperonin interacts with HIV-1 RT and theref ore affects the folding process of HIV-1 RT.