Messenger RNAs transcribed from yeast linear cytoplasmic plasmids possess unconventional 5’ and 3’ UTRs and suggest a novel mechanism of translation

Václav Vopálenský; Michal Sýkora; Tomáš Mašek; Martin Pospíšek

The most straightforward explanation of the obtained results is that whereas in this experiment, K1 toxin mRNA is transcribed from the shuttle plasmid under the control of a TPI promoter by the nuclear RNA polymerase II and is thus 5' capped, 3' polyadenylated, and translated exclusively by the canonical cap-dependent pathway, pGKL1 toxin mRNAs retain their ability to be translated even when 5' mRNA cap recognition is severely impaired. The poly(A) tails, a common mark of most eukaryotic mRNAs (114). In addition, PABP1 serves as a specific regulatory protein and has an important role in mRNA stability and turnover. The importance of PABP1 in cellular translation and other vital processes is underlined by growing evidence that it is targeted by a wide range of viruses aiming to take over host protein synthesis or to escape the cellular antiviral defense (115-118).