Cleavage of a 23S rRNA pseudoknot by phenanthroline-Cu(II)

摘要

Studying the intricate folding of rRNA within the ribosome remains a complex problem. Phenanthroline-Cu(II) complexes cleave phosphodiester bonds in rRNA in specific regions, apparently especially where the rRNA structure is constrained in some fashion. We have introduced phenanthroline-copper complexes into 50S Escherichia coli ribosomal subunits and shown specific cleavages in the regions containing nucleotides 60–66 and 87–100. This specificity of cleavage is reduced when the ribosome is heated to 80°C and reduced to background when the ribosomal proteins are extracted and the cleavage repeated on protein-free 23S rRNA. It has been suggested that nucleotides 60–66 and 87–95 in E.coli 23S rRNA are involved in a putative pseudoknot structure, which is supported by covariance data. The paired cleavages of nearly equal intensity of these two regions, when in the ribosome, may further support the existence of a pseudoknot structure in the 100 region of 23S rRNA.