As mRNA (orange) enters the ribosome's downstream tunnel, it is unwound.

NOLLER/ELSEVIER

Helicase activity is embedded within the ribosome, based on results from Seyedtaghi Takyar, Harry Noller, and colleagues (University of California, Santa Cruz, CA).

The trouble with mRNAs, at least from a translation point of view, is that they have extensive secondary structure. The ribosomal slot through which the mRNA passes is too narrow to allow anything wider than a single strand. Yet no one had identified the relevant RNA helicase activity. “It's kind of a long-overlooked problem,” says Noller. “No one got down to how the structure is unwound.”

Now, he shows that the ribosome itself does the unwinding. Using purified proteins and labeled oligos bound to mRNAs (to mimic helices), the group demonstrates that the ribosome alone can release the oligo (unwind the helix) during translation.

This activity was mapped to the...

The Rockefeller University Press
2005
The Rockefeller University Press
2005
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