Host: Prof. Dr. Kai Johnsson

CB Seminar with Martin Distel (Children's Cancer Research Institute)

CB Seminar with Martin Distel (Children's Cancer Research Institute)
Title of the talk: Modeling Cancer in Zebrafish – current strategies and novel tools [more]

CB Seminar with Thomas Carell (LMU München)

CB Seminar with Thomas Carell (LMU München)
Title: DNA Bases beyond Watson and Crick T. Carell, Center for Integrative Protein Science at the Department of Chemistry, Ludwig Maximilians University, Munich, Butenandtstr. 5-13, 81377; e-mail: thomas.carell@lmu.de; www.carellgroup.de Keywords: Epigenetics, oxidized pyrimidine bases, mass spectrometry, proteomics. Abstract: Epigenetic information is stored in the form of modified bases in the genome. The positions and the kind of the base modifications determines the identity of the corresponding cell. Setting and erasing of epigenetic imprints controls the complete development process starting from an omnipotent stem cells and ending with an adult specialized cell. I am going to discuss results related to the function and distribution of the new epigenetic bases 5-hydroxymethylcytosine (hmC), 5-formylcytosine (fC), 5-carboxycytosine (caC) and 5-hydroxymethyluracil (Scheme 1).[1] These nucleobases seem to control epigenetic programming of cells and establish genetic programmability. Synthetic routes to these new bases will be discussed that enable the preparation of oligonucleotides. The second part of the lecture will cover mass spectroscopic approaches to decipher the biological functions of the new bases.[2] In particular, results from quantitative mass spectrometry, new covalent-capture proteomics mass spectrometry and isotope tracing techniques will be reported.[3] Finally I am dicussing potential präbiotic origins of modified bases[4]. [more]

Rudolf Mößbauer Colloquium with Andrea Musacchio (MPI of Molecular Physiology) - The kinetochore: the ultimate divisive machine

Rudolf Mößbauer Colloquium with Andrea Musacchio (MPI of Molecular Physiology)
During mitotic cell division, each daughter cell receives from its mother cell an exact, full copy of the genome. For this to happen, the sister chromatids in the mother cell must bi-orient on the mitotic spindle. Sister chromatid separation at the metaphase-to-anaphase transition then leads to equal segregation of the genome to the two daughters. Chromosome attachment to spindle microtubules takes place at complex protein structures named kinetochores, which contain multiple copies of as many as ~30 individual core subunits. This stable protein core emerges from a specialized region of the chromosome known as the centromere. Microtubule binding by kinetochores is subject to a feedback control mechanism known as error correction (ER), and whose purpose is to detect improper configurations of the attachments and allow their regression. This mechanism is believed to require a force sensor capable of monitoring differences in the action of forces acting on kinetochores when they are bi-oriented (correct attachments) or not (incorrect attachment). The molecular nature of this force sensor remains unclear. In addition, kinetochores determine the timing of mitotic exit by exercising control over the cell cycle machinery through the spindle assembly checkpoint (SAC). The SAC coordinates completion of bi-orientation with the transition to anaphase, preventing premature mitotic exit in the presence of incompletely attached sister chromatid pairs. All SAC components are recruited to kinetochores and regulated there in a way that reflects attachment status but that remains poorly understood. In the last several years, our laboratory engaged in the in vitro reconstitution and in the structural and functional characterization of several kinetochore sub-complexes that operate at the interface between chromatin and microtubules. We also reconstituted crucial aspects of SAC signalling, identifying a rate-limiting step in the pathway, as well as a set of catalysts that accelerate the accumulation of the checkpoint effector, the mitotic checkpoint complex (MCC). Our current efforts aim to unravel the role of kinetochores in SAC signalling, using reconstituted material as our entry point in the investigation. I will report on the conceptual challenges associated with this idea, as well as on our recent experimental progress. [more]

CB Departmental Seminar with Richard Wombacher (IPMB) on 'Protein Labelling and -Manipulation in Living Cells Using Bioorthogonal Chemistry'

CB Departmental Seminar with Richard Wombacher (IPMB) on 'Protein Labelling and -Manipulation in Living Cells Using Bioorthogonal Chemistry'
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