title: Insights on HIV-1 Tat:P/CAF bromodomain molecular recognition from in vivo experiments and molecular dynamics simulations.
abstract: Structural and functional studies indicate that, through its bromodomain, the cellular acetyltransferase P/CAF binds the acetylated Tat protein of human immunodeficiency virus type 1 (HIV-1) and promotes transcriptional activation of the integrated provirus. Based on the NMR structure of P/CAF complexed with an acetylated Tat peptide, here we use molecular dynamics simulations to construct a model describing the interaction between full length Tat and the P/CAF bromodomain. Our calculations show that the protein-protein interface involves hydrophobic interactions between the P/CAF ZA loop and the Tat core domain. In particular, tyrosines 760 and 761 of P/CAF, two residues that are highly conserved in most known bromodomains, play an essential role for the binding. Fluorescence resonance energy transfer (FRET) experiments performed in this work demonstrate that P/CAF proteins in which these tyrosines are mutated into hydrophilic residues neither bind to Tat inside the cells nor mediate Tat transactivation. The combination of theoretical and in vivo studies provides new insights into the specificity of bromodomain recognition.
authors.affiliation: International School for Advanced Studies, INFM-DEMOCRITOS Modeling Center for Research in Atomistic Simulation, Trieste, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Pantano
authors.forename: Alessandro
authors.initials: A
authors.lastname: Marcello
authors.forename: Aldo
authors.initials: A
authors.lastname: Ferrari
authors.forename: Daniele
authors.initials: D
authors.lastname: Gaudiosi
authors.forename: Arianna
authors.initials: A
authors.lastname: Sabò
authors.forename: Vittorio
authors.initials: V
authors.lastname: Pellegrini
authors.forename: Fabio
authors.initials: F
authors.lastname: Beltram
authors.forename: Mauro
authors.initials: M
authors.lastname: Giacca
authors.forename: Paolo
authors.initials: P
authors.lastname: Carloni
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D015696:Gene Products, tat / Q000737:chemistry* / Q000235:genetics; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D012333:RNA, Messenger / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D012996:Solutions; D014867:Water; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015696:Gene Products, tat; D021122:Protein Subunits; D012333:RNA, Messenger; D012367:RNA, Viral; D012996:Solutions; D054322:tat Gene Products, Human Immunodeficiency Virus; D014867:Water