Departmental Seminar: Dr. Guillermo Calero

Event Date: 4.21.2014 Day:Monday Time: 12:00 pm Location: 601 Fairchild Event Type: Departmental

Dr. Guillermo Calero
Department of Structural Biology
University of Pittsburgh School of Medicine

Title: “Nanocrystallography and New Frontiers in Structural Biology”

Host: Dr. John Hunt

Abstract
The emergence of X-ray free electron laser (X-FEL) based serial femtosecond crystallography opens the possibility of solving the three-dimensional structures of samples that can only crystallize as nanocrystals (NCs). Given the new opportunities that X-FELs offer to the field of crystallography, my laboratory is using transmission electron microscopy (TEM) to identify NCs from granular precipitates observed in crystallization trials. Moreover, since crystalline lattices can be directly visualized with TEM, calculating Fourier transforms from the images allows quantitative evaluation of electron diffraction patterns (Bragg spots). Identifying NCs from granular precipitates opens the possibility of finding NCs with different crystals forms. This is of paramount importance since different NC forms could potentially yield higher resolution X-ray diffraction. In addition to the advantages that TEM brings to the field of nanocrystallography, NC imaging may be beneficial during conventional crystallization trials to improve crystallization conditions and provide useful crystal 'seeds' for the production of macro-crystals. Using these methodologies we have been able to crystallize and solve the structure of novel multi-protein complexes involved in eukaryotic transcription. This work could uncover the potential of TEM as a fundamental tool for evaluating NC, as essential as brightfield microscopy is for evaluating and optimizing traditional, large crystals.