REPLACEMENT OF HIS23 BY CYS IN A ZINC-FINGER OF HIV-1 NCP7 LED TO A CHANGE IN H-1 NMR-DERIVED 3D STRUCTURE AND TO A LOSS OF BIOLOGICAL-ACTIVITY

The nucleocapsid protein NCp7 of human immunodeficiency virus type 1 ( HIV-1), which is necessary for the formation of infectious virions, co ntains two zinc fingers of the Cys-X2-Cys-X4-His-X4-Cvs form. To eluci date the importance of this particular motif, well conserved in retrov iruses and retroelements, we substituted the histidine residue by a cy steine in the first zinc binding domain 13VKCFNCGKEGHTARNCRA30. The st ructures of the mutated and native zinc complexed peptides were studie d by two-dimensional 600 MHz H-1 nuclear magnetic resonance (NMR) in a queous solution. The nuclear Overhauser effects were used as constrain ts to determine the solution structures using DIANA software followed by AMBER energy refinement. The results show that native and mutant pe ptides fold into non-identical three-dimensional structures, probably accounting for the loss of retrovirus infectivity following the His-Cy s point mutation.