Seminars & Events Archive
Events Calendar
Dongyan Tan, PhD - Harvard Medical School |
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Monday, March 09, 2015, 02:00pm - 03:00pm |
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"Utilizing the Breakthroughs in Single-Particle Electron Microscopy to Study the Structures and Dynamics of Molecular Machines" Abstract: Advances in detector hardware and image-processing software have revolutionized the field of cryo-EM (electron microscopy). By combining these recent advancements we have determined the structure of a AAA+(ATPases Associated with diverse cellular Activity) protein complex Pex1/Pex6 at 7.3 Å resolution and built a pseudo-atomic model using the novel model building software RosettaCM. Pex1 and Pex6 alternate in an hexameric double-ring in the model. The N-terminal ATPase domains are inactive, forming a symmetric D1 ring, while the C-terminal domains are active, likely in different nucleotide states, and form an asymmetric D2 ring. These results suggest how subunit activity is coordinated and indicate striking similarities between Pex1/Pex6 and p97. The powerful and versatile single-particle EM technique is also very useful in obtaining structural information of challenging biological samples. This is demonstrated through the second part of the talk, using the INO80-C and SWR-C complexes as examples. These two enzymes are conserved members of a subfamily of ATP-dependent chromatin-remodeling enzymes that play key roles in transcription and genome-maintenance pathways. Our results demonstrate that these two remodeling enzymes have similar overall architectures. Each enzyme is characterized by a long, dynamic 'tail' domain and a compact 'head' that contains the Rvb1/Rvb2 subunits organized as hexameric rings. By combining the structural and functional data, our work implicates the Ies6/Arp5 module of INO80-C in regulating conformational changes that couple nucleosome binding to remodeling. Hosts: Mike Kilejdian and Stephen Burley Download Seminar Notice |
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Proteomics 120 | |||||||||
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