High-speed direct detector for cryo electron microscopy

PROJECT ABSTRACT We are requesting funds to acquire a Gatan K3 Summit direct electron detector to interface with the Titan Krios electron microscope at Scripps Research. This detector would significantly advance the research programs of 17 NIH-funded investigators and aid numerous other researchers secure preliminary data for future NIH grant

applications. The highly efficient automated data acquisition and real-time processing infrastructure at Scripps has enabled much of our faculty to integrate cryo-EM structure determination methodologies into their research programs, and as a result, the demand on the cryo-EM facility continues to increase every year. The EM facility

at Scripps Research currently maintains two electron microscopes capable of generating high-resolution single particle cryo-EM structures - a Titan Krios and an Talos Arctica, both of which acquire images with ~10-year-old Gatan K2 Summit direct detectors. However, despite nearly 24/7 operation of these two instruments, microscope

access has become increasingly limited due to high user demand. Currently, users must wait ten to twelve weeks between cryo-EM data collection sessions, which is consequentially detrimental to the progress of dozens of ongoing NIH-funded projects within the Institute. The requested K3 detector has improved detective quantum

efficiency, inline GPU-based motion correction, faster read-out rates, and a larger field of view than the existing K2 camera. Together, we estimate that these improvements will result in a ~5.6-fold increase in the rate of data collection on the Titan Krios, enabling acquisition of thousands more datasets per year than currently possible.

Acquisition of this K3 camera would also enable us to mount the existing K2 on our Talos 200C microscope, further increasing the efficacy of our EM facility and benefiting our researchers. Many samples, particularly biological targets smaller than ~250 kilodaltons, cannot be assessed for quality using the low-end CCD cameras

on our other microscopes. These preliminary screenings currently must be done using the two high-resolution microscopes and consequently occupies precious time that could otherwise be directed towards more developed projects. Transfer of the current K2 to our Talos F200C would provide the EM facility with a direct detector-

enabled screening microscope dedicated to sample optimization, dramatically increasing our researchers’ ability to identify appropriate conditions for structure determination on the Titan Krios and Talos Arctica. Scripps Research has a long-standing commitment to cryo-EM technologies, which is demonstrated by the Institute’s

commitment to covering the shortfall associated with purchasing the Gatan K3 and four years of service contracts (the total cost of which is significantly more than the maximum budget of this grant). The Institute has also committed to allocating funds to cover a monthly “Discovery Day” on the Titan Krios, which will provide

researchers with the opportunity to generate preliminary data to pursue NIH grant funding for exploratory projects. By providing our investigators with the necessary microscope access, this upgrade will have a transformative impact on dozens of NIH-funded projects carrying significant biomedical relevance.