New photoactivatable structural and affinity probes of RNAs: specific features and applications for mapping of spermine binding sites in yeast tRNA(Asp) and interaction of this tRNA with yeast aspartyl-tRNA synthetase.

Aryldiazonium salts are shown to be useful as phototriggered structural probes for RNA mapping as well as for footprinting of RNA/protein interaction. In particular the yeast tRNA(Asp)/aspartyl-tRNA synthetase complex is shown to involve the variable loop face and the concave side of the L-shaped nucleic acid bound to a lipophilic area of the enzyme. When chemically linked to spermine, the photoactive group cleaves RNA at polyamine binding sites; 3-4 spermines have been located in the tRNA(Asp), stabilizing the central part of the molecule in regions where two ribose-phosphate strands are close to each other.