University College Cork, Ireland 

Kate O’Connor is a PhD Student in Biochemistry at the University College Cork, in Ireland.  She visited the EMBL Imaging Centre in December 2021 and May 2023.

Her project aimed to determine the structure of the ribosome translating MGS13 mRNA (a novel case of bypassing) with the stem-loop in the A site paused before take-off. Bypassing is an rare phenomenon in translation involving dissociation of peptidyl-tRNA anticodon:codon interactions, followed by mRNA slippage and re-pairing of the peptidyl-tRNA with a non-overlapping codon downstream. The ribosome undergoes a long rotated state pause prior to anticodon:codon dissociation.

What was the specific scientific challenge that you could overcome thanks to our service? 

Although we did not succeed in capturing the structure of the ribosome primed for bypassing of MGS13 mRNA, we did determine the structure of the bacterial ribosome at an unprecedented resolution of 1.55 Å thanks to the incredible facilities available at the EMBL Imaging Centre and the fantastic work carried out by Simon Fromm. 

Which imaging technologies in the EMBL Imaging Centre did you apply? 

Cryo-EM single particle.

Which new technique/sample preparation did you learn at the EMBL Imaging Centre and will you be able to apply it in the further course of your studies?

Grid preparation and using the screening microscope. 

What results did you achieve using our services and could you publish those?

The structure of the ribosome obtained at a resolution of 1.55 Å to the best of our knowledge is the highest reported resolution of the ribosome or any non-symmetrical complex by single particle cryo-EM. These results have been published in Nature Communications DOI: 10.1038/s41467-023-36742-3. 

How long did you stay with us and how did you like staying on site/in Heidelberg?

I stayed in Heidelberg for a couple of weeks. Simon Fromm and Simone Mattei, along with all of the Imagine Centre staff, were very welcoming and were incredibly knowledgeable and informative. Accommodation and flights were organised by the Imaging Centre so the visit was made very easy, and it was great to get the opportunity to explore the beautiful city of Heidelberg. 

Anything else you would like the future users of EMBL Imaging Centre to know?

The facilities available at the EMBL Imaging Centre are state of the art. No prior knowledge of single particle Cryo-EM is necessary to use the facilities. I just had to provide the sample, and staff at the Imaging Centre took care of grid preparation, grid screening, and data collection.