Ribonucleopeptides: functional RNA-peptide complexes

Selection of functional RNAs from randomized pool of RNA molecules successfully affords RNA aptamers that specifically bind to small molecules, and that have catalytic activities. Recent structural analyses of the ribosomal RNA complex suggest that the RNA-protein complex would be a new structural candidate for the design of tailor-made receptors and enzymes. We have designed an ATP binding domain that consists of an RNA subunit and a peptide subunit by means of structure-based design approach and successive in vitro selection method. The RNA subunit is designed to consist of two functional domains; an ATP binding domain with 20 randomized nucleotides and an adjacent stem region that serves as a binding site for the RNA-binding peptide. The randomized nucleotide region was placed next to the HIV-1 Rev response element to enable the formation of "ribonucleopeptide" pools in the presence of the Rev peptide. In vitro selection of RNA oligonucleotides from the randomized pool afforded a ribonucleopeptide receptor specific for ATP. The ATP-binding ribonucleopeptide did not share the known consensus nucleotide sequence for ATP aptamers, and completely lost its ATP-binding ability in the absence of the Rev peptide. The ATP-binding activity of the ribonucleopeptide was increased by a substitution of the N-terminal amino acid of the Rev peptide. These results demonstrate that the peptide stabilizes the functional structure of RNA and suggest that amino acids outside the RNA binding region of the peptide participate in the ATP binding. Our approach would provide a new strategy for the design of tailor-made ribonucleopeptide receptors.