title: HIV-1 Tat peptide binding to TAR RNA by electrospray ionization mass spectrometry.
abstract: Electrospray ionization mass spectrometry (ESI-MS) has been used to study the noncovalent complexes formed from the interaction between HIV-1 Tat peptide and Tat protein with TAR RNA. Both positive ion and negative ion ESI mass spectra showed a maximum stoichiometry of 3:1 between Tat peptide and TAR RNA. However, the higher order complexes only occurred at high relative concentrations of Tat peptide. The 1:1 Tat peptide-TAR RNA complex is believed to involve only specific interactions, whereas the higher order complexes involve nonspecific interactions. Relative binding affinities between Tat peptide and TAR RNA and its various mutants (TAR missing the three-nucleotide bulge, TAR with a poly(ethylene glycol) linker in the bulge region, and TAR with a poly(ethylene glycol) linker in the loop region) can be differentiated by competitive binding experiments and ESI-MS measurements. The gas phase mass spectrometry experiments are consistent with solution phase studies, as they show that mutations in the bulge region reduce TAR RNA affinity to Tat peptide.
authors.affiliation: Chemistry Department, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, Michigan 48105, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Sannes-Lowery
authors.forename: P
authors.initials: P
authors.lastname: Hu
authors.forename: D P
authors.initials: DP
authors.lastname: Mack
authors.forename: H Y
authors.initials: HY
authors.lastname: Mei
authors.forename: J A
authors.initials: JA
authors.lastname: Loo
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015696:Gene Products, tat / Q000378:metabolism*; D016325:HIV Long Terminal Repeat / Q000235:genetics; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding; D012367:RNA, Viral / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015696:Gene Products, tat; D010455:Peptides; D012367:RNA, Viral; D011993:Recombinant Fusion Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus