Towards molecular characterization of HIV-vif interaction with human Apobec-3G

Poster number: 29

C. Cramer von Laue (1), A. Friebe (1), D. Hoffmann (1,2), B. Heil (1), T. Hohm (1), R. Frank (3), H. Hennemann (1)

  1. centre of advanced european studies and research, Ludwig-Erhard-Allee 2, D-53175 Bonn, Germany
  2. Bingen University of Applied Sciences, Berlinstr. 109, D-55411 Bingen am Rhein, Germany
  3. Department of Chemical Biology, GBF (Gesellschaft für Biotechnologische Forschung), Mascheroder Weg 1, D-38124 Braunschweig, Germany

Human cytidine deaminase Apobec-3G induces DNA hypermutation in retroviruses and thus provides a cellular defence mechanism against these pathogens. HIV has overcome this shield by generating the Viral Infectivity Factor (vif) protein that binds to Apobec-3G and eventually accelerates proteasome-mediated degradation of Apobec-3G.

There is currently no high-resolution structural information available, neither on vif nor on Apobec-3G. We have tried to characterize the interface of vif responsible for binding to Apobec-3G by a combination of bioinformatics and experimental methods. First, we have prepared a peptide array of 60 spots of 15 amino acids long overlapping fragments of a vif protein sequence. The binding of 35S-labelled recombinant Apobec-3G to these vif-derived peptides was analysed. In parallel we have carried out 3D-structure predictions of vif and a multiple sequence alignment of more than one thousand vif sequences and in this way derived a profile and consensus sequence.

We have then correlated the degrees of sequence conservation with measured affinities, and observed in several sequence areas both a strong affinity and a high degree of conservation. These matches provide hints at possible binding interfaces. Experimentally testable hypotheses on binding motifs compatible with these data are presented.