Evidence for stacking interactions between 5‐mercurated polyuridylic acid and HIV‐1 p7 nucleocapsid protein obtained by phosphorescence and optically detected magnetic resonance (ODMR)

FEBS Letters

Casas-Finet, José R.¹  Lam, Wai-Chung²  Henderson, Louis E.¹  Erickson, John W.¹  Sowder, Raymond C.¹  Maki, August H.² 

[1] PRI/DynCorp. Natlonal Cancer Institute-FCRDC, Frederick, MD 21702, USA;Department of Chemistry, University of California, Davis, CA 95616, USA

关键词: External heavy atom effect;    Tryptophan phosphorescence;    ODMR spectroscopy;    Zinc finger-RNA interaction;    5-HgU;    5-mercurated polyuridylic acid;    HIV-1;    human immunodeficiency virus type-1;    HAE;    heavy atom effect;    ME;    2-mercaptoethanol;    MIDP;    microwave-induced delayed phosphorescence;    NC;    nucleocapsid;    ODMR;    optically detected magnetic resonance of the photoexcited triplet state;    SLR;    spin-lattice relaxation;    SSB;    E. coli single-stranded DNA-binding protein;    ZFS;    zero-field splittings;   

DOI  :  10.1016/0014-5793(93)80962-T

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The photoexcited triplet state of Trp-37 in the C-terminal zinc finger of the HIV-1 p7 nucleocapsid protein was used as a probe of p7 interactions with the heavy atom-derivatized RNA homopolymer, poly-5-mercuriuridylic acid (5-HgU). Binding of p7 to 5-HgU (Hg blocked with 2-mercaptoethanol) produces an external heavy atom effect (HAE) on Trp-37 characterized by fluorescence quenching, reduction of the phosphorescence lifetime by three orders of magnitude, and the appearance of the D + E phosphorescence-detected ODMR signal, absent in unperturbed Trp, but induced by a HAE. The details of the HAE are consistent with out-of-plane van der Waals contact of Hg with the indole chromophore of Trp-37. Steric requirements suggest further that the Trp-RNA contact occurs via an aromatic stacking interaction.

【 授权许可】

Unknown