Translational control

The ribosome has been a driver for single-particle cryo-EM methods development since the 1970s. We have a long-standing collaboration with the Korostelev lab (University of Massachusetts Medical School) on translational control of gene expression by the ribosome. In a recent example, we visualized the stepwise decoding of cognate aminoacyl-tRNA [1] [2]. Using the “focused mask” feature of Frealign, we were able to resolve small structural differences between three states of tRNA accommodation in the A site of the small subunit of a bacterial ribosome. The accommodation of cognate tRNA, and rejection of other tRNAs is a fundamental requirement for fidelity in ribosomal translation. Our work suggests that the 30S subunit only efficiently closes when a cognate tRNA is bound, moving the elongation factor EF-Tu into position to be activated for GTP hydrolysis by the sarcin-ricin loop.