Self-containment and modularity of RNA

Miler Lee, University of Pennsylvania

An RNA molecule is made up of a linear sequence of nucleotides, which form pairwise interactions that define its “folded” three-dimensional structure. Many alternate structures are possible; however, biologically functional RNAs will tend to assume one particular structure, which is generally the most thermodynamically stable one. How any particular string of nucleotides will fold can also depend on whether it exists in isolation, or whether it is a substring of a longer sequence. Some subsequences will tend to form interactions with the surrounding sequence, some will be structurally invariant regardless of sequence context. We investigate this “self-containment” property of RNAs and show it to be a characteristic distinguishing evolved, biological RNAs from artificial ones. We relate this property to the idea that RNAs exhibit some degree of “modularity,” such that individual substructures can be combined together to form larger units maintaining the structural characteristics of the pieces.

Abstract Author(s): Miler T. Lee and Junhyong Kim