Ribosome translating mRNAWIKIMEDIA, NICOLLE RAGER, NATIONAL SCIENCE FOUNDATIONInterruption of the protein translation machinery as it reads a messenger RNA (mRNA) transcript is rare but problematic. A new study in Science Advances today (July 24) reveals that one cause for such arrest is the mRNA sequence itself—specifically, strings of multiple adenosine (A) nucleotides. Although such translation stalling on poly(A) stretches had been observed previously, it was thought that the encoded amino acids were to blame. The finding that in fact the nucleotides are responsible could have important implications for gene mutations previously considered silent, or synonymous.
“That it’s really the RNA sequence and not the protein sequence which is important—that was a serendipitous finding, and what’s beautiful . . . is that they followed it up,” said cell and molecular geneticist Jonathan Dinman of the University of Maryland who was not involved in the work. “They were looking for one thing . . . but found the unexpected.”
Ribosomes, the proteins that read the codon sequences of mRNA transcripts and translate them into amino acid chains, occasionally stall. And when they do, the general result is degradation of both the mRNA and the unfinished protein. There are several reasons for ribosomal arrest, including mutations to the mRNA sequence or impassable secondary structures formed by aberrant folding of the RNA. However, stalling ...
