Chen, J,Coakley, A,O'Connor, M,Petrov, A,O'Leary, SE,Atkins, JF,Puglisi, JD

2015

November

Cell

Coupling of mRNA Structure Rearrangement to Ribosome Movement during Bypassing of Non-coding Regions

Validated

WOS: 28 ()

SINGLE-MOLECULE FLUORESCENCE OPEN READING FRAMES EXIT TUNNEL COMPOSITIONAL DYNAMICS NASCENT PEPTIDE CODING GAP REAL-TIME TRANSLATION TRANSLOCATION MAINTENANCE

163

1267

1280

Nearly half of the ribosomes translating a particular bacteriophage T4 mRNA bypass a region of 50 nt, resuming translation 30 of this gap. How this large-scale, specific hop occurs and what determines whether a ribosome bypasses remain unclear. We apply single-molecule fluorescence with zeromode waveguides to track individual Escherichia coli ribosomes during translation of T4's gene 60 mRNA. Ribosomes that bypass are characterized by a 10- to 20-fold longer pause in a non-canonical rotated state at the take-off codon. During the pause, mRNA secondary structure rearrangements are coupled to ribosome forward movement, facilitated by nascent peptide interactions that disengage the ribosome anticodon-codon interactions for slippage. Close to the landing site, the ribosome then scans mRNA in search of optimal base-pairing interactions. Our results provide a mechanistic and conformational framework for bypassing, highlighting a non-canonical ribosomal state to allow for mRNA structure refolding to drive large-scale ribosome movements.

10.1016/j.cell.2015.10.064