LESSONS FROM AN EVOLVING RIBOSOMAL-RNA - 16S AND 23S RIBOSOMAL-RNA STRUCTURES FROM A COMPARATIVE PERSPECTIVE

Underlying the functional complexity of large macromolecules, such as the rRNAs, is their structure. underpinning the complex structure of t he rRNAs is a fundamental set of RNA structure principles that transfo rms a sequence of nucleotides into an intriguing and puzzling assembla ge of RNA structure. Currently, our understanding of these principles of RNA structure is rudimentary. Utilizing those known to transform a primary structure into its higher-order structure, while improving, re mains far from an exact science The 16S and 23S rRNAs, the focus of th ese studies, have, like other biological entities, evolved to their pr esent state. The process of mutation and selection has molded these hi gher-order structures into their present forms. Although we do not nec essarily understand the pathways or the selection pressures of this ev olutionary process, analysis of a large collection of structurally hom ologous 16S (and 16S-like) and 23S (and 23S-like) rRNAs is quite revea ling. The secondary and other higher-order structure far these large R NA molecules, over 1,500 and 2,900 nucleotides in length, respectively , are presented herein, along with a few emerging principles of (r)RNA structure.