title: HIV-1 p6-Another viral interaction partner to the host cellular protein cyclophilin A.
abstract: The 52-amino acid human immunodeficiency virus type 1 (HIV-1) p6 protein has previously been recognized as a docking site for several cellular and viral binding factors and is important for the formation of infectious viruses. A particular structural feature of p6 is the notably high relative content of proline residues, located at positions 5, 7, 10, 11, 24, 30, 37 and 49 in the sequence. Proline cis/trans isomerism was detected for all these proline residues to such an extent that more than 40% of all p6 molecules contain at least one proline in a cis conformation. 2D (1)H nuclear magnetic resonance analysis of full-length HIV-1 p6 and p6 peptides established that cyclophilin A (CypA) interacts as a peptidyl-prolyl cis/trans isomerase with all proline residues of p6. Only catalytic amounts of CypA were necessary for the interaction with p6 to occur, strongly suggesting that the observed interaction is highly relevant in vivo. In addition, surface plasmon resonance studies revealed binding of full-length p6 to CypA, and that this binding was significantly stronger than any of its N- or C-terminal peptides. This study demonstrates the first identification of an interaction between HIV-1 p6 and the host cellular protein CypA. The mode of interaction involves both transient enzyme-substrate interactions and a more stable binding. The binding motifs of p6 to Tsg-101, ALIX and Vpr coincide with binding regions and catalytic sites of p6 to CypA, suggesting a potential role of CypA in modulating functional interactions of HIV-1.
authors.affiliation: Department of Chemistry and Centre of Pharmacy, University of Bergen, Bergen, Norway.
authors.forename: Sara M Ø
authors.initials: SM
authors.lastname: Solbak
authors.forename: Tove R
authors.initials: TR
authors.lastname: Reksten
authors.forename: Rene
authors.initials: R
authors.lastname: Röder
authors.forename: Victor
authors.initials: V
authors.lastname: Wray
authors.forename: Ole
authors.initials: O
authors.lastname: Horvli
authors.forename: Arnt J
authors.initials: AJ
authors.lastname: Raae
authors.forename: Petra
authors.initials: P
authors.lastname: Henklein
authors.forename: Peter
authors.initials: P
authors.lastname: Henklein
authors.forename: Torgils
authors.initials: T
authors.lastname: Fossen
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D021984:Cyclophilin A / Q000737:chemistry*; D015497:HIV-1 / Q000201:enzymology / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007536:Isomerism; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D012997:Solvents / Q000737:chemistry; D020349:Surface Plasmon Resonance; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000737:chemistry*
chemical_list: D010446:Peptide Fragments; D012997:Solvents; D054301:gag Gene Products, Human Immunodeficiency Virus; C083002:p6 gag protein, Human immunodeficiency virus 1; D021984:Cyclophilin A