Dmitry Lyumkis, Platform Speaker

Dmitry_LyumkisDmitry Lyumkis, Platform Speaker,
International Symposium on Cryo-Em 3D Image Analysis
Lake Tahoe, CA 
March 12-15, 2014 
Multi-step 3D classification facilitates identification and characterization of cofactors involved in translation quality control 

The presentation focused on the structural characterization of the multi-subunit Ribosome-Associated Quality Control (RQC) complex, which is responsible for eliminating aberrant proteins remaining stalled in the ribosomal 60S subunit after synthesis. The talk elaborated on the use of single-particle cryo-EM techniques to describe the architecture of the RQC complex and to delineate its multiple associated components. The structural analysis required the use and development of techniques enabling the characterization of multiple distinct particle populations from a single EM data set using multi-step 3D classifications, thus allowing us to make sense of a very heterogeneous cryo-EM data set. The information enabled us to put together a model for how the RQC functions within the context of protein quality control.

Dmitry Lyumkis, Platform Speaker
Keystone Symposia, Frontiers in Structural Biology
Snowbird, Utah
March 30 – April 4, 2014

Direct Detectors and Single-Particle Dissection of Compositional Heterogeneity: Cryo-EM structure of the HIV Trimer

The presentation was focused on the structure of the HIV-1 envelope glycoprotein (Env) trimer at 5.8 Å resolution. The talk was particularly focused on the methodological advances that made it possible to solve the structure of the trimer, specifically: the use of tightly binding Fabs to increase the signal and facilitate computational image processing; the use of direct detectors to account for beam-induced motion and specimen drift; the use of image processing techniques to account for compositional heterogeneity present within the data. Functional interpretations were also addressed. The ability to describe the trimer in atomic level detail provides a structural basis for understanding Env biology and designing trimeric vaccine immunogens.