Sharmeen L, Heldsinger A, Neorr B, McQuade T, Gracheck S; Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Co., Ann Arbor, MI.
The zinc finger motif of retroviral nucleocapsids is an attractive target for antivirals. Several genetic studies with mutations in zinc fingers support multiple effects of nucleocapsids in the virus life cycle. It is difficult to reconcile some of the genetic and biochemical results unless zinc fingers of nucleocapsid proteins have dual functions in RNA binding and in reverse transcription processes. Targeting the zinc coordinated amino acids with compounds such as CI-1012 showed the antiviral effect is due to inhibition of the reverse transcription process without effects on packaged RNA. To understand the role of zinc coordinating amino acids and positively charged amino acids of zinc fingers, several mutations of zinc coordinating amino acids were constructed by oligo directed mutagenesis in molecular clone of HIV-Bru virus. These mutations include changes in Cys to Gly and His to Asn residues in the first zinc finger, His to Gly in the second zinc finger, His to Glu in both zinc fingers, and changes of the basic amino acid linker region between two zinc fingers RAPRKK to RAPGGG. The effect of the above mutations on several aspects of the virus cycle including gag expression and processing, virus assembly and production, virus infectivity, and RNA packaging were determined. Mutations in zinc coordinating amino acids had no effect on virus production but caused a 60-80% loss in infectivity due to inefficient reverse transcription of virion RNA. Mutations of basic amino acids of the zinc finger resulted in an 80-90% decrease in packaged RNA. We propose that the ionic environment of zinc coordinating amino acids are essential for productive infection whereas basic region participates in the RNA packaging processes.
Keywords: AEGIS, Nucleocapsid, HIV, Zinc Fingers, Zinc, HIV-1, Virus Assembly, Amino Acids, Virion, HIV Long Terminal Repeat, Mutation, HIV Infections, virology, genetics, AIDS
