Catalyzing the Understanding of Enzyme Kinetics : A Consistent Application of Constructive Alignment and Its Evaluation

In this study, the principles of constructive alignment were applied to an introductory lecture offered every year for bachelor students in the Faculty of Biosciences at Heidelberg University. The introductory lecture is part of a course that consists of the lecture followed by a practical laboratory session on the topic of enzyme kinetics. This course sequence is repeatedly taught over five weeks to 25-40 students each week. The motivation to use this course as a didactical experiment stemmed from the observations I made in previous years that (1) only a fraction of the students actively participated during the lecture and (2) a significant portion of the students did not grasp key concepts. Hence, I started this project by asking myself how I could design my teaching in a way that would engage the most students in active learning and would help them understand what I wanted to convey. To achieve this goal, I decided to apply the concept of constructive alignment by John Biggs. To do so, I redesigned the introductory lecture to first introduce learning objectives (LOs) and then broke down the lecture in blocks that covered each LO and were followed by a dedicated teaching-learning activity (TLA). In this report, I present the design and outcomes of the re-designed lecture and discuss successes, limitations, and potential improvements

GIGYF2 mediates post-transcriptional mRNA repression through recruitment of the CCR4/NOT complex

ABSTRACTInitially identified as a factor involved in tyrosine kinase receptor signalling, GRB10-interacting GYF protein 2 (GIGYF2) has later been shown to interact with the 5’ cap-binding protein m4EHP as part of a translation repression complex, and to mediate post-transcriptional repression of tethered reporter mRNAs. We recently observed that GIGYF2 also interacts with the miRNA-induced silencing complex and modulates its translation repression activity. Here we have further investigated how GIGYF2 represses mRNA function. In RNA tethering reporter assays we show that GIGYF2 exerts its action through a combination of translational repression and stimulated mRNA decay. Using truncation variants we identify two distinct effector domains within GIGYF2. In this assay GIGYF2-mediated repression is independent of m4EHP but dependent on the deadenylation activity of the CCR4/NOT complex. We further show that GIGYF2 interacts with multiple subunits of the CCR4/NOT complex and interestingly depletion of the CNOT1 scaffold subunit does not affect GIGYF2-mediated repression. Finally, we identify endogenous mRNA targets of GIGYF2 that recapitulate m4EHP - independent repression. Altogether, we propose that GIGYF2 has two distinct mechanisms of repression: one depends on m4EHP binding and affects translation, the other is m4EHP-independent and relies on the deadenylation activity of the CCR4/NOT complex.</jats:p

Coatomer, the Coat Protein of COPI Transport Vesicles, Discriminates Endoplasmic Reticulum Residents from p24 Proteins

In the formation of COPI vesicles, interactions take place between the coat protein coatomer and membrane proteins: either cargo proteins for retrieval to the endoplasmic reticulum (ER) or proteins that cycle between the ER and the Golgi. While the binding sites on coatomer for ER residents have been characterized, how cycling proteins bind to the COPI coat is still not clear. In order to understand at a molecular level the mechanism of uptake of such proteins, we have investigated the binding to coatomer of p24 proteins as examples of cycling proteins as well as that of ER-resident cargos. The p24 proteins required dimerization to interact with coatomer at two independent binding sites in γ-COP. In contrast, ER-resident cargos bind to coatomer as monomers and to sites other than γ-COP. The COPI coat therefore discriminates between p24 proteins and ER-resident proteins by differential binding involving distinct subunits