Maturation-induced Conformational Changes of HIV-1 Capsid Protein and Identification of Two High Affinity Sites for Cyclophilins in the C-terminal Domain

Michael M. Endrich, Peter Gehrig, Heinz Gehring
1999 Journal of Biological Chemistry  
Viral incorporation of cyclophilin A (CyPA) during the assembly of human immunodeficiency virus type-1 (HIV-1) is crucial for efficient viral replication. CyPA binds to the previously identified Gly-Pro 90 site of the capsid protein p24, but its role remained unclear. Here we report two new interaction sites between cyclophilins and p24. Both are located in the C-terminal domain of p24 around Gly-Pro 157 and Gly-Pro 224 . Peptides corresponding to these regions showed higher affinities (K d ϳ
more » ... affinities (K d ϳ 0.3 M) for both CyPA and cyclophilin B than the best peptide derived from the Gly-Pro 90 site (ϳ8 M) and thus revealed new sequence motifs flanking Gly-Pro that are important for tight interaction of peptide ligands with cyclophilins. Between CyPA and an immature (unprocessed) form of p24, a K d of ϳ8 M was measured, which corresponded with the K d of the best of the Gly-Pro 90 peptides, indicating an association via this site. Processing of immature p24 by the viral protease, yielding mature p24, elicited a conformational change in its C-terminal domain that was signaled by the covalently attached fluorescence label acrylodan. Consequently, CyPA and cyclophilin B bound with much higher affinities (ϳ0.6 and 0.25 M) to the new, i.e. maturation-generated sites. Since this domain is essential for p24 oligomerization and capsid cone formation, CyPA bound to the new sites might impair the regularity of the capsid cone and thus facilitate in vivo core disassembly after host infection.
doi:10.1074/jbc.274.9.5326 pmid:10026140 fatcat:jhzsd6gvmbgktkc6jb3hsdqqja