Targeted Sister Chromatid Cohesion by Sir2

The protein complex known as cohesin binds pericentric regions and other sites of eukaryotic genomes to mediate cohesion of sister chromatids. In budding yeast Saccharomyces cerevisiae, cohesin also binds silent chromatin, a repressive chromatin structure that functionally resembles heterochromatin of higher eukaryotes. We developed a protein-targeting assay to investigate the mechanistic basis for cohesion of silent chromatin domains. Individual silencing factors were tethered to sites where pairing of sister chromatids could be evaluated by fluorescence microscopy. We report that the evolutionarily conserved Sir2 histone deacetylase, an essential silent chromatin component, was both necessary and sufficient for cohesion. The cohesin genes were required, but the Sir2 deacetylase activity and other silencing factors were not. Binding of cohesin to silent chromatin was achieved with a small carboxyl terminal fragment of Sir2. Taken together, these data define a unique role for Sir2 in cohesion of silent chromatin that is distinct from the enzyme's role as a histone deacetylase

A role for the Saccharomyces cerevisiae RENT complex protein Net1 in HMR silencing.

Silencing in the yeast Saccharomyces cerevisiae is known in three classes of loci: in the silent mating-type loci HML and HMR, in subtelomeric regions, and in the highly repetitive rDNA locus, which resides in the nucleolus. rDNA silencing differs markedly from the other two classes of silencing in that it requires a DNA-associated protein complex termed RENT. The Net1 protein, a central component of RENT, is required for nucleolar integrity and the control of exit from mitosis. Another RENT component is the NAD(+)-dependent histone deacetylase Sir2, which is the only silencing factor known to be shared among the three classes of silencing. Here, we investigated the role of Net1 in HMR silencing. The mutation net1-1, as well as NET1 expression from a 2micro-plasmid, restored repression at silencing-defective HMR loci. Both effects were strictly dependent on the Sir proteins. We found overexpressed Net1 protein to be directly associated with the HMR-E silencer, suggesting that Net1 could interact with silencer binding proteins and recruit other silencing factors to the silencer. In agreement with this, Net1 provided ORC-dependent, Sir1-independent silencing when artificially tethered to the silencer. In contrast, our data suggested that net1-1 acted indirectly in HMR silencing by releasing Sir2 from the nucleolus, thus shifting the internal competition for Sir2 from the silenced loci toward HMR

Verfahren zur Herstellung kontaktloser Chipkarten und kontaktlose Chipkarte

The production of a novel, non-contact smart card (1) is claimed. The electrically-insulating, flat card is made with at least one recess(es) on one side. Conductive track(s) are applied in a given pattern, on the surface of the recessed side. The track(s) are applied on surfaces both within and outside the recess(es). Microcircuit chip(s) (4) are aligned in the recess(es) and brought into contact with the track(s). Also claimed is a contact-less smart card, essentially as described. USE - Used to make a contact-less smart card with potentially extremely wide application in private and public life. ADVANTAGE - The process manufactures non-contact smart cards, producing the coils especially, at low cost. Resistance to mechanical stress and reliability are good. Single stage processes are employed where possible. Hot Stamp coil application is particularly economic and adhesive on the coil underside completes attachment. High production rates are achieved. The coil transfers data and/or e nergy, acting as an antenna. Of various applicable mounting technologies, the flip-chip method is particularly compact. Contact bumps are conveniently and accurately formed and registered during the earlier hot-stamping stage. Hermetic sealing using glob top technology, increases the reliable life of the card

Herstellung galvanisch abgeformter Kontakthoecker

The contact bumps are intended for the bottom of integrated circuits, the metal deposition is formed on a metallising subsequently located under the contact bump, using external current-free process. Preferably an Ni or Au deposition is carried out on the metal bond pad, typically of Al, as an under-bump metallising, prior to depositing a thin plating base (5) in an external current-free process, the metal of the plating base is to be so selected that there is no permanent diffusion between under-metallising and metal contact bumps. USE/ADVANTAGE - For flip-chip or TAB technique, without need for high cost sputtering