Seminars and other activities
Two major activities are carried out in the group: Biophysics seminars by invited speakers and group meetings.
NEXT SEMINARS:
Date and place:
Wednesday 22nd June 2011, 15h Aula 320,
Planta 3, Facultat de Fisica
Speaker:
Hendrik Dietz, TU Munchen
Title:
Sequence, shape, function: a primer to DNA origami
Abstract:
Advanced molecular self-assembly with ÔDNA origamiÕ offers a unique route for building custom shaped high-complexity objects that are commensurate in size to biological macromolecules. DNA origami objects can be used as platforms for placing, orienting, and even manipulating biological molecules in user defined ways. Thus, DNA origami objects can not only help improve existing experimental methods in the molecular biosciences but they also open completely new avenues of exploration.
In our laboratory we have set out to develop custom 'nanoÕ instrumentation based on DNA origami that complements single-molecule-level methods for observing and manipulating biological macromolecules. Among other goals, we seek to enable the study of adhesive interactions between biomolecules in unprecedented detail. We also aim to develop tools for unraveling the conformational dynamics of proteins at work in novel ways. More long term, we hope to be able to create a biologically inspired nanotechnology including devices that are capable of performing complex tasks such as enzymatic catalysis or molecular transport for human purposes.
In my lecture I will focus on an introduction to DNA origami, our near-term applications, and report about some of our efforts in analyzing and improving molecular self-assembly reactions with DNA origami.
Date and place:
Tuesday 22nd February 2011, 12h Aula 320,
Planta 3, Facultat de Fisica
Speaker:
Marcelo Nollmann, Centre de Biochimie Structurale (CNRS). Montpellier
Title:
Understanding DNA segregation during bacterial cell division with single-molecule super-resolution microscopy
Abstract:
ATP-fuelled molecular motors are responsible for rapid and specific transfer of double-stranded DNA during several fundamental processes, such as cell division, sporulation, bacterial conjugation, and viral DNA transfer. A dramatic example of intercompartmental DNA transfer occurs during sporulation in Bacillus subtilis, in which 3Mbp of chromosomal DNA are transported across a division septum by the SpoIIIE ATPase. We previously showed that SpoIIIE translocates DNA at 5kbp/s while specifically interacting with highly skewed chromosomal sequences (SRS) that guide its directional motion. In addition, our data suggested that SpoIIIE assembles on a compartment-specific manner, though other reports proposed a different scenario. Here, we use photoactivated localization microscopy, a recently developed super-resolution microscopy method, to directly visualize the architecture and the assembly dynamics of the SpoIIIE complex in live cells.
Date and place:
Thursday 11th November 2010, 15h Aula 320,
Planta 3, Facultat de Fisica
Speaker:
Matthias Rief, Technische Universitat Muenchen
Title:
Near equilibrium fluctuations of single protein molecules
Abstract:
Single molecule mechanical experiments allow the observation of protein fluctuations over extended periods. In my talk I will show how the full free energy landscape of a single molecule of the GCN4 leucine zipper can be extracted using dual beam optical tweezers. To this end, we employed deconvolution force spectroscopy to follow an individual molecule's trajectory with high temporal and spatial resolution. We find a heterogeneous energy landscape of the GCN4 leucine zipper domain. The energy profile is divided into two stable C-terminal heptad repeats and two less stable repeats at the N-terminus. Energies and transition barrier positions were confirmed by single molecule kinetic analysis.
Date and place:
Tuesday 19th October 2010, 12h Aula 320,
Planta 3, Facultat de Fisica
Speaker:
J. Ricardo Arias-Gonzalez, IMDEA Nanoscience (Madrid, Spain)
Title:
The B-A transition in DNA: a study at the single-molecule level
Abstract:
Double-stranded DNA has the significant ability of changing its structural levels of organization: from a random-coiled polymer with polymorphic secondary structure to general networks of fibrous aggregates which can lead to tight particles with toroidal or rodlike geometry. DNA secondary structure and its transitions among its different forms have constituted a central problem in molecular and structural biology. In this seminar we study the transition between physiological B-DNA and A-DNA, the latter of which is a structure which can be induced by both base sequence and water activity. We use a combination of bulk analysis (Circular Dichroism) and single-molecule techniques (Atomic Force Microscopy, Magnetic and Optical Tweezers) to study how the local, base-stacking configuration, either B or A, affect the global conformational state of the molecule. We analyze the influence of water activity by using water-ethanol mixtures and polycationic agents, and the influence of sequence by using plasmid DNAs which differ in G·C composition.
GROUP MEETINGS
Place
SALA DE SEMINARIS, Aula 320, planta 3
Dpto.Fisica Fonamental, Facultat de Fisica