Celebrating ten years of Krios I

Ten years after the arrival of Diamond’s first Titan Krios microscope, eBIC reflects on a decade of pioneering cryo-electron microscopy. From groundbreaking reconstructions to over 200 academic citations, Krios I has transformed structural biology in the UK and beyond.

The eBIC team with Krios I

A decade ago, Diamond welcomed its first Titan Krios microscope marking a big step forward for structural biology in the UK. 

Known as Krios I, it was the first fully automated transmission electron microscope at Diamond. The technology enabled rapid, stable, high-resolution imaging of frozen samples at cryogenic temperatures. It also marked the beginning of eBIC’s journey as a world-class centre for cryo-electron microscopy. 

Within its first year, Krios I made headlines by producing the highest-resolution 3D reconstruction of GroEL proteins using cryo-EM. That early success demonstrated the microscope’s potential for structural biology breakthroughs.  

One of its standout achievements was collecting data using the world’s first EPU-embedded BioQuantum-K2 detector, another first for eBIC. Researchers captured the sample as a series of digital films, essentially creating a high-resolution, frame-by-frame view of the molecular structure in motion. These were recorded in super-resolution counting mode, which picked up individual electrons, and a 30 eV energy filter was used to enhance the image. Advanced software then turned that data into a 3D model. 

From around 30,000 particles, 17,500 were selected to build a 3.2 Ångström resolution model of GroEL, a protein complex that helps other proteins fold properly. At the time, it was the highest-resolution 3D model of GroEL ever made using cryo-EM, and a major milestone for Krios I. 

Since then, Krios I has played a key role in hundreds of high-impact studies, helping researchers explore the structures of proteins, viruses, and drug targets. It’s been a valuable tool for both academic and industrial teams, speeding up data collection and cutting costs, which has helped accelerate discoveries across the field. 

The first paper citing Krios I was published just months after installation. This early study looked at pili, the tiny hair-like structures on bacteria that help them latch onto host tissues. Understanding how these structures work could lead to new ways to prevent infections. Thanks to Krios I, researchers discovered that pili are shaped like springs, helping bacteria cling on even in tough conditions. 

Krios I has established itself as a cornerstone at both eBIC and Diamond, It has seen 6,875 grids and recorded more than 7.5 million movies. Its influence is reflected by more than 200 citations in academic publications in the last ten years. This record is a testament to its contribution to furthering structural biology research and excellence.