ANALYSIS OF SEQUENCE REQUIREMENTS FOR BIOLOGICAL-ACTIVITY OF CYANOVIRIN-N, A POTENT HIV (HUMAN IMMUNODEFICIENCY VIRUS)-INACTIVATING PROTEIN

Site-directed mutagenesis of DNA constructs coding for the novel, HIV- inactivating proteins cyanovirin-N (CV-N) and FLAG-cyanovirin-N (F-CV- N) was performed using mutagenic oligonucleotide primers in the polyme rase chain reaction or by a restriction site elimination maneuver. The mutant constructs were expressed in Escherichia coli and the recombin ant protein products were tested for binding to the HIV surface envelo pe glycoprotein gp120 and for antiviral activity against infectious HI V. Results showed an overall very high correlation (r(2) > 0.9) betwee n the relative gp120 binding affinities and the anti-HIV activities of CV-N, F-CV-N, and the various mutants. An outlier, however, was a mut ant which lacked one of the internal disulfide linkages normally prese nt in CV-N and which showed modest gp120 binding but no antiviral acti vity against HIV. These findings are consistent with the view that gp1 20 binding is a necessary but not sufficient requirement for the HIV-i nactivating activity of CV-N and related proteins; the sequence specif icities for gp120 binding and anti-HIV activity are not identical. (C) 1997 Academic Press.