לוח שנה משולב

Researchers hypothesized that the first protein domains arose by joining and swapping short lengths of proteins called peptides that had emerged before there were living cells on earth – a time that is often called the “RNA world”. However, the properties of the first proteins remain poorly understood, in part because of the difficulty in studying events that happened billions of years ago.
Combining bioinformatics, structural biology and experimental approaches we developed a model system for the first proteins in order to understand the functional and structural transitions that drive protein emergence and evolution.

Moist processes, and in particular the release of latent heat in ascending airstreams, can modify the mid-latitude flow and contribute to the formation of prolonged circulation anomalies such as atmospheric blocking. Blocking represents a challenge to numerical weather and climate forecasting, because it may lead to high impact weather in a situation of increased forecast uncertainty. The causal link between latent heating and blocking is still not well understood. In this study, we explore the effect of latent heating in ascending airstreams on the characteristics of atmospheric blocking using a combination of climatological analysis and modelling approaches. The results of this study illustrate how the physics within ascending airstreams play a crucial role in the formation of blocking anticyclones and in the upper-level wave dynamics in general.

FOOD EVOLUTION is set amidst a brutally polarized debate marked by fear, distrust and confusion: the controversy surrounding GMOs and food.

WASP-Interacting Protein (WIP) is a multifunctional key participant in mediating actin-related cytoskeletal changes in human T cells. WIP is also an intrinsically disordered protein (IDP), lacking any significant secondary or tertiary structure across its 503 residues, and thus defies the ordinarily reliable structure-function paradigm. Our research focuses on how interactions between this ‘hub’ multi-tasker and its various structured binding partners delicately control T cell destiny, in particular the role played by disorder-to-order transitions. Three such critical protein-protein contacts involve the WIP N-terminal domain (with actin), a proline-rich central segment (with cortactin) and the C-terminal domain (with Wiskott-Aldrich syndrome protein, WASP). The first two are of intermediate binding energy (KD ~ 50-3000 nM) and transiently modulate WIP interactions with the actin polymerization machinery. In contrast, the latter forms a tight complex with WASP and inhibits both its activity and eventual degradation in a phosphorylation-dependent manner, explaining why the hereditary Wiskott-Aldrich syndrome immunodeficiency results from WASP mutants unable to bind WIP.
As an IDP, WIP ‘structure’ is essentially an ensemble of multiple conformations contributing to function, and this complexity gives solution NMR – armed with new IDP-optimized methodologies – unrivaled insight into how IDPs exert their biological influence. We established that transient structure in free WIPN and WIPC echoes their bound conformations, uncovering novel binding epitopes in the process. We also observed subtle ensemble shifts induced by environmental factors, such as temperature, denaturant or crowding agents, revealing the biophysics governing WIP behavior in the cellular environment. We further investigated the largest conformational change, experienced by WIPC upon binding to WASP, by determining the contribution of various WIP epitopes to complex affinity, and eventually the structure of the WIP-WASP complex. Finally, we offer an unexpected structural explanation for phosphorylation-induced dissociation of this complex that may explain how this phospho-switch controls WASP degradation. Taken together our results provide a comprehensive map of WIP structure and dynamics and how these affect its interaction with T cell binding partners, and highlight the great impact of high-resolution NMR studies upon the field of biologically active unstructured proteins.

Micro-algae greatly influence present and past oceans. Recently we have come to realize that bacteria interact with micro-algae in various ways, ranging from pathogenicity to mutualism. My research investigates physical and chemical interactions between micro-algae and bacteria across multiple scales; from the chemical crosstalk to the influence these interactions have on the marine environment.
In my talk I will introduce Emiliania huxleyi, the most prevalent micro-alga in modern oceans. I will discuss the role of bacteria as hidden farmers that control the life cycle of algae, determining how fast algae will grow and how fast they will die. I will link laboratory findings to work conducted at sea and demonstrate the importance of these findings in the study of proxies for climate reconstructions.