פרסומים

Initiation of transcription in Escherichia coli is facilitated by promoter specificity factors, such as σ⁷⁰, which bind promoter dsDNA when in complex with RNA polymerase (RNAP), in which it is in an extended conformation with solvent-exposed DNA-interacting residues. If so, what in the structure of apo-σ⁷⁰ prevents binding to promoter dsDNA at high affinity? By performing cross-linking mass spectrometry (CL-MS) and integrative structural modelling we elucidate structure models of apo-σ⁷⁰ that exhibit burial of almost all DNA-binding residues. In vivo CL-MS detects crosslinks unique to the compact fold of apo-σ⁷⁰ that occur at stationary growth phase. Conclusively, we provide structural information to show that the high affinity DNA-binding capabilities of apo-σ⁷⁰ are conformationally-inhibited and can be activated mostly in the context of transcription.

Super-resolution light microscopy techniques facilitate the observation of nanometer-size biomolecules, which are 1-2 orders of magnitude smaller than the diffraction limit of light. Using super-resolution microscopy techniques it is possible to observe fluorescence from two biomolecules in close proximity, however not necessarily in direct interaction. Using FRET-sensitized acceptor emission localization (FRETsael), we localize biomolecular interactions exhibiting FRET with nanometer accuracy, from two color fluorescence lifetime imaging data. The concepts of FRETsael were tested first against simulations, in which the recovered localization accuracy is 20-30 nm for true-positive detections of FRET pairs. Further analyses of the simulation results report the conditions in which true-positive rates are maximal. We then show the capabilities of FRETsael on simulated samples of Actin-Vinculin and ER-ribosomes interactions, as well as on experimental samples of Actin-Myosin two-color confocal imaging. Conclusively, the FRETsael approach paves the way towards studying biomolecular interactions with improved spatial resolution from laser scanning confocal two color fluorescence lifetime imaging.

How and why do people still get print newspapers in an era dominated by mobile and social media communication? In this article, we answer this question about the permanence of traditional media in a digital media ecosystem by analyzing 488 semi-structured interviews conducted in Argentina, Finland, Israel, Japan, and the United States. We focus on three mechanisms of media reception: access, sociality, and ritualization. Our findings show that these mechanisms are decisively shaped by patterns of everyday life that are not captured by the scholarly foci on either content- or technology-influences on media use. Thus, we argue that a non-media centric approach improves descriptive fit and adds heuristic power by bringing a wider lens into crucial mechanisms of media reception in ways that expand the conceptual toolkit that scholars can utilize to analyze the role of media in everyday life.