Psoralen cross-linking of ribosomal RNA.

This method allows one to isolate helical interactions in RNA molecules under numerous conditions. The cross-linking of RNA with psoralen followed by isolation and sequencing of the cross-linked fragments is a powerful method for determining interactions within the RNA that elude chemical and enzymatic mapping techniques. With the data produced by this method and its variations, features of the secondary structure of the rRNAs have been confirmed and some long-range interactions have given insight into tertiary interactions within rRNAs. Limitations of the method include the specificity of the psoralen photoreaction. This limits the method described to those sites in the folded RNA molecule where psoralens photoreact best.