A5058871813- Photosynthetic Processes and Mechanisms
- Force Microscopy Techniques and Applications
- DNA and Nucleic Acid Chemistry
- Plant Stress Responses and Tolerance
- Nuclear Structure and Function
- Spectroscopy and Quantum Chemical Studies
- Biocrusts and Microbial Ecology
- Algal biology and biofuel production
- Mechanical and Optical Resonators
- Molecular Junctions and Nanostructures
- RNA and protein synthesis mechanisms
- Light effects on plants
- Photoreceptor and optogenetics research
- T-cell and B-cell Immunology
- Protein Structure and Dynamics
- Bacteriophages and microbial interactions
- Monoclonal and Polyclonal Antibodies Research
- RNA Research and Splicing
- Immune Cell Function and Interaction
- RNA regulation and disease
- Advanced biosensing and bioanalysis techniques
- Plant responses to water stress
- Antioxidant Activity and Oxidative Stress
- Microbial Community Ecology and Physiology
- Immunotherapy and Immune Responses
Weizmann Institute of Science
2016-2025
United States Nuclear Regulatory Commission
2015
Howard Hughes Medical Institute
1997-1999
Stanford University
1997-1999
Paul Ehrlich Institut
1998
California Institute of Technology
1997
Tokyo University of Science
1997
European Molecular Biology Laboratory
1992
The machinery that conducts the light-driven reactions of oxygenic photosynthesis is hosted within specialized paired membranes called thylakoids. In higher plants, thylakoids are segregated into two morphological and functional domains grana stroma lamellae. A large fraction luminal volume granal occupied by oxygen-evolving complex photosystem II. Electron microscopy data we obtained on dark- light-adapted Arabidopsis indicate thylakoid lumen significantly expands in light. Models generated...
While much is known about intracellular signaling events in T cells when cell receptors (TCRs) are engaged, the mechanism by which initiated unclear. We have constructed defined oligomers of soluble antigen-major histocompatibility complex (MHC) molecules, natural ligands for TCR. Using these to stimulate specific vitro, we find that agonist peptide/MHC nonstimulatory as monomers and minimally stimulatory dimers. Similarly, a partial-agonist ligand very weakly active tetramer. In contrast,...
Abstract The light-harvesting and energy-transducing functions of the chloroplast are performed within an intricate lamellar system membranes, called thylakoid which differentiated into granum stroma domains. Using dual-axis electron microscope tomography, we determined three-dimensional organization membranes cryo-immobilized, freeze-substituted lettuce (Lactuca sativa) leaves. We found that grana built repeating units consist paired layers formed by bifurcations sheets, fuse body. These...
Abstract Adaptability of oxygenic photosynthetic organisms to fluctuations in light spectral composition and intensity is conferred by state transitions, short-term regulatory processes that enable the apparatus rapidly adjust variations quality. In green algae higher plants, these are accompanied reversible structural rearrangements thylakoid membranes. We studied changes membranes Arabidopsis thaliana chloroplasts using atomic force microscopy, scanning transmission electron confocal...
The earliest visual changes of leaf senescence occur in the chloroplast as chlorophyll is degraded and photosynthesis declines. Yet, a comprehensive understanding sequence catabolic events occurring chloroplasts during natural still missing. Here, we combined confocal electron microscopy together with proteomics biochemistry to follow structural molecular Arabidopsis senescence. We observed that initiation catabolism precedes other breakdown processes. Chloroplast size, stacking thylakoids,...
Antigen-dependent activation of T lymphocytes requires cell receptor (TCR)-mediated recognition specific peptides, together with the MHC molecules to which they are bound. To achieve this in a reasonable time frame, TCR must scan and discriminate rapidly between thousands differing from each other only their bound peptides. Kinetic analysis interaction its cognate peptide-MHC complex indicates that both association dissociation depend heavily on temperature, indicating presence large energy...
Bacterial plasmids may often reach a copy number larger than 1000 per cell, corresponding to total amount of DNA that exceed the within bacterial chromosome. This observation highlights problem cellular accommodation large amounts closed-circular nucleic acids, whose interwound conformation offers negligible compaction. As determined by x-ray scattering experiments conducted on intact bacteria, supercoiled segregate cells into dense clusters characterized long-range order. In vitro studies...
Chloroplasts of higher plants develop from proplastids, which are undifferentiated plastids that lack photosynthetic (thylakoid) membranes. In flowering plants, the proplastid-chloroplast transition takes place at shoot apex, consists apical meristem (SAM) and flanking leaf primordia. It has been believed SAM contains only proplastids these become chloroplasts in primordial leaves. Here, we show neither homogeneous nor necessarily null. Rather, their developmental state varies with specific...
Significance The fitness and robustness of plants crucially depend on the molecular repair vulnerable photosystem II (PS II) supercomplex, embedded in photosynthetic thylakoid membranes. To maintain performance, evolved an efficient multistep PS cycle. cycle relies a well-defined order reactions partial separation individual steps. By combining biochemical, spectroscopic, ultrastructural techniques, we discover that establish reaction by confinement enzymes catalyze steps to spatially...
Upon exposure to light, plant cells quickly acquire photosynthetic competence by converting pale etioplasts into green chloroplasts. This developmental transition involves the de novo biogenesis of thylakoid system and requires reprogramming metabolism gene expression. Etioplast-to-chloroplast differentiation massive changes in plastid ultrastructure, but how these are connected specific physiology, metabolism, expression nuclear genomes is poorly understood. Here, we describe a new...
Significance The intricate structure of the membrane network that hosts primary steps photosynthesis in plant chloroplasts has intrigued scientists for decades. Here, we used electron tomography to determine this structure. We found is consolidated by arrays right- and left-handed helical structures. Similar arrangements pitch-balanced elements alternating handedness were proposed be present endoplasmic reticulum and, remarkably, ultradense nuclear matter. These thus likely represent a...
The success of synthetic DNA delivery systems in human gene therapy will be enhanced by increasing transfection efficiencies and providing tighter control over targeting the into nucleus. Here, we used vectors that contain repetitive binding sites for inducible transcription factor NFκB, which is transported nucleus nuclear import machinery. Nuclear entry modified was augmented 12-fold associated with corresponding increase expression. Depending on their position, could also function as...
The use of synthetic gene delivery systems in human transfer is hampered by poor transfection efficiencies, largely because the inability DNA to translocate across nuclear pore complex. A means overcome this barrier bind localization signals (NLSs), which are recognized shuttling receptors import machinery. Here, we studied intracellular transport plasmid microinjected into HeLa cell cytoplasm, alone or as a complex with intact NLS-deleted NFκB p50, using confocal microscopy imaging. We...
In the present study we evaluated DNA binding activity of wild type and mutant p53 proteins that were isolated from bacterial expression vectors. A comparison activities various purified proteins, assessed by their ability to bind cellulose columns, Indicated has a higher affinity than have forms. Furthermore, only was able genomic upon electrophoretlc protein blotting. As specific deletion C-terminal region totally abolished DNA, it concluded 47 C-termlnal amlno acids contain region. The...
Entropic stabilization of native protein structures typically relies on strategies that serve to decrease the entropy unfolded state. Here we report, using a combination experimental and computational approaches, enhanced thermodynamic stability conferred by an increase in configurational folded The is observed upon modifications loop region enzyme acylphosphatase achieved despite significant enthalpy losses. lead increased stability, as well those result destabilization, however, strongly...