Structural and functional studies of retroviral RNA pseudoknots involved in ribosomal frameshifting: nucleotides at the junction of the two stems are important for efficient ribosomal frameshifting.

摘要: Ribosomal frameshifting, a translational mechanism used during retroviral replication, involves directed change in reading frame at specific site defined frequency. Such programmed frameshifting the mouse mammary tumor virus (MMTV) gag-pro shift requires two mRNA signals: heptanucleotide shifty sequence and pseudoknot structure positioned downstream. Using vitro translation assays enzymatic chemical probes for RNA structure, we have features of that promote efficient frameshifting. Heterologous structures, e.g. hairpin, tRNA or synthetic pseudoknot, substituted downstream fail to suggesting MMTV are important function. Site-directed mutations indicate junction, including an unpaired adenine nucleotide between stems, provides structural determinant Pseudoknots derived from other retroviruses (i.e. feline immunodeficiency simian retrovirus type 1) also site, dependent on same junction stems.