Cryoelectron Microscopic Examination of Human Immunodeficiency Virus Type 1 Virions with Mutations in the Cyclophilin A Binding Loop

Abstract

The human immunodeficiency virus type 1 capsid protein contains a conserved P 217 X 4 PX 2 PX 5 P 231 motif. Mutation at Pro-222 decreases virion incorporation of cyclophilin A, while mutation at Pro-231 abolishes infectivity. Although viral RNA incorporation and protease cleavage of the Gag precursor were not affected by these mutations, cryoelectron microscopy revealed a loss of virion maturation in P231A particles.