Public Seminars

Further course details can be found on the web at http://www2.mrc-lmb.cam.ac.uk/groups/murshudov/

Further course details can be found on the web at http://www2.mrc-lmb.cam.ac.uk/groups/murshudov/

Synopsis:
CCP4MG is a molecular graphics program which quickly and easily generates publication quality images and movies. Pictures can be created with a variety of effects for added realism: shadows, occlusion, complex lighting effects, etc.The program can also superpose molecular structures, display and align sequences, perform blast searches and much more.

Further course details can be found on the web at http://www2.mrc-lmb.cam.ac.uk/groups/murshudov/

Synopsis:
During the process of evolution the structure of a genome may undergo
substantial changes including alterations in chromosome numb (aneuploidy). It has been shown that aneuploidy can confer fitness advantages under certain environmental conditions; however, it also comes with a cost as it introduces gene expression imbalances within the cell. To address this dichotomy we evolved S. cerevisiae cells for thousands of generations under diverse conditions and followed the long-term evolutionary dynamics of changes in chromosome number and gene expression. We found that specific stresses select for rapid duplication of particular chromosomes. Yet, these duplications are reversible events even findings suggest that chromosomal duplication, selected under stress, is a transient trait which serves as a "quick and dirty" evolutionary intermediate to help cells cope with stress until a more cost-efficient solution can be established .

Synopsis:
Arrestins function as adapter proteins that facilitate desensitization, internalization and signaling of G protein-coupled receptors (GPCRs). Quenching of G protein signaling via arrestins is best understood in the visual system where arrestin-1 quenches phototransduction via its ability to bind to the phosphorylated, light-activated form of the visual photoreceptor rhodopsin. Using pull downs of an arrestin-mCherry fusion protein, we have compared rhodopsin binding of 403 mutants covering the complete arrestin sequence. Iterative combination of mutations allowed us to engineer super binding arrestins with many potential applications in structural biology, diagnostics and drug development. Our analysis furthermore provides a functional 4th dimension to the crystal structures of inactive1, preactivated2 and active arrestins3. The resulting single amino acid resolution functional maps reveal a series of critical interactions in the polar core and along the C-tail of arrestin that are interrupted during arrestin activation. Phosphosensing is achieved by a C-tail exchange mechanism in which the release of the arrestin C-tail exposes several charged amino acids for binding of the phosphorylated receptor C-terminus. Our data further reveals several patches of amino acids that strongly reduce binding and likely act as direct binding interfaces to rhodopsin. We discuss these interfaces in context of a model of the arrestin-rhodopsin complex derived from molecular docking with the crystal structures of active arrestin3 and light-activated rhodopsin4.

Further course details can be found on the web at http://www2.mrc-lmb.cam.ac.uk/groups/murshudov/

Abstract: In this talk we will describe the use of combinatorial antibody libraries to endow cells with new binding energy landscapes for the purpose of regulating their phenotypes. Antibodies that are expressed in cells infected with a lentiviral combinatorial antibody library are selected directly for function rather than only for binding. Many different agonist antibodies were selected using this method including TPO, EPO, G-CSF, integrin, and neurogenesis phenocopies.. The most powerful format is an autocrine based selection system.

Further course details can be found on the web at http://www2.mrc-lmb.cam.ac.uk/groups/murshudov/

Synopsis:
Cytoplasmic dynein is a large and versatile intracellular motor protein. Compared with other cytoskeletal motors, it is unusual in that a single motor gene is responsible for diverse functions ranging from transporting membranous cargo within neurons, to organizing microtubules within the mitotic spindle, to polarizing mRNAs during development. Therefore, a nascent idea is that cytoplasmic dynein is a large macromolecular machine that can be tuned to meet its varied demands in cells. The lissencephaly protein, Lis1, is a universal dynein co-factor that may have such a tuning role, although how it regulates dynein is unclear and controversial. In this seminar, I will present experiments aimed at elucidating how Lis1 regulates dynein motility, using data from a combination of techniques including single-molecule imaging and single-particle electron microscopy. These experiments reveal that Lis1 binds at the interface between dynein’s ATP-hydrolyzing “engine” and its microtubule-binding stalk. With Lis1 bound, individual dynein motors remain attached to microtubules for extended periods, even during cycles of ATP hydrolysis that would canonically induce detachment. Thus, Lis1 operates like a “clutch” that prevents dynein’s ATPase domain from transmitting a detachment signal to its track-binding domain. These findings provide a mechanism for dynein functions in living cells that require prolonged microtubule attachments.