The 2A Story: The End of the Beginning

Abstract

Translational control of viral gene expression is a fundamental process essential for the vitality of all viruses. In special cases, signals encoded in the mRNA reprogram the ribosome to read the message in a different way, a process termed “translational recoding”. The 2A region of the foot-and-mouth disease virus (FMDV) encodes a short sequence, only 18 amino acids, that mediates self-processing by a novel translational effect “ribosome skipping” rather than proteolysis. Briefly, 2A interacts with the ribosome exit tunnel to inhibit peptide bond formation at the C terminus of the 2A sequence. Translation terminates at this point, but then resumes elongation, creating a second independent protein product. Thus, discrete proteins can be produced from a single transcript. The 2A sequence is particularly useful in vector strategies (AAV and retroviral vectors) where the capacity to incorporate foreign DNA is limited. Use of 2A and “2A-like” peptides to link the sequences encoding several proteins in the same open reading frame has led to their increasing use as important tools in biotechnology and biomedicine. This technology has been crucial for the visual tracking of expressed proteins, human gene therapies targeting cancer, production of induced human pluripotent stem cells for regenerative medicine, creation of transgenic animals and plants and the improvement of CRISPR-Cas9 and TALEN genome editing methods.