STAPHYLOCOCCAL PROTEIN-A IS A NOVEL HETEROLOGOUS SUBSTRATE FOR THE HIV-1 PROTEASE

Upon in vitro processing of the recombinant HIV-1/gag p24 protein, exp ressed in Escherichia coli as a fusion protein, by HIV-1 protease, a c leavage site within the staphylococcal protein A fusion partner was fo und. N-terminal sequencing of the protein A fragments showed that HIV- 1 protease cleavage occurred between phenylalanine-235 and tyrosine-23 6 within the sequence Gln-Asn-Ala-Phe/Tyr-Glu-Ile-Leu (QNAF/YEIL) in t he IgG-binding domain C of the protein A encoded by the pRIT2T fusion gene vector (Pharmacia). Results presented here have proven that the p rotease-sensitive site is viable in vitro on the protein A alone and o ther chimeric protein, protein A/beta-galactosidase. A possible signif icance of this phenomenon in biotechnology work is discussed.