Published online 19 July 2006
© 2006 The Author(s)
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TAR-RNA recognition by a novel cyclic aminoglycoside analogue
Department of NMR-based Structural Biology, The Max Planck Institute for Biophysical Chemistry Am Fassberg, 11 D-37077 Göttingen, Germany 1 Institute of Organic Chemistry, University of Hannover Schneiderberg 1B, D-30167 Hannover, Germany
*To whom correspondence should be addressed. Tel: +49 551 201 2214; Fax: +49 551 201 2202; Email: taco{at}nmr.mpibpc.mpg.de
Received March 13, 2006. Revised May 30, 2006. Accepted June 27, 2006.
The formation of the Tat-protein/TAR-RNA complex is a crucial step in the regulation of human immunodeficiency virus (HIV)-gene expression. To obtain full-length viral transcripts the Tat/TAR complex has to recruit the positive transcription elongation factor complex (P-EFTb), which interacts with TAR through its cyclin T1 (CycT1) component. Mutational studies identified the TAR hexanucleotide loop as a crucial region for contacting CycT1. Interfering with the interaction between the Tat/CycT1 complex and the TAR-RNA is an attractive strategy for the design of anti-HIV drugs. Positively charged molecules, like aminoglycosides or peptidomimetics, bind the TAR-RNA, disrupting the Tat/TAR complex. Here, we investigate the complex between the HIV-2 TAR-RNA and a neooligoaminodeoxysaccharide by NMR spectroscopy. In contrast to other aminoglycosides, this novel aminoglycoside analogue contacts simultaneously the bulge residues required for Tat binding and the A35 residue of the hexanucleotide loop. Upon complex formation, the loop region undergoes profound conformational changes. The novel binding mode, together with the easy accessibility of derivatives for the neooligoaminodeoxysaccharide, could open the way to the design of a new class of TAR-RNA binders, which simultaneously inhibit the formation of both the Tat/TAR binary complex and the Tat/TAR/CycT1 ternary complex by obstructing both the bulge and loop regions of the RNA.
Present address: Víctor M. Sánchez-Pedregal, Universidad de Santiago de Compostela, Facultad de Química, Departmento Química Orgánica, Campus Universitario Sur, s/n Postcode E-15782 Santiago de Compostela, Spain