Cell type-specific chromatin organization of the region that governs directionality of yeast mating type switching. |
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Authors: | K Weiss and R T Simpson |
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Institution: | Department of Biochemistry and Molecular Biology and Center for Gene Regulation, Penn State University, University Park 16802, USA. |
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Abstract: | Switching of mating type in Saccharomyces cerevisiae is directional; MAT alpha cells recombine to transfer information from HMRa while MATa cells switch using the silent cassette at HML alpha. Genetic analysis recently has defined a 700 bp recombination enhancer approximately 29 kb from the left end of chromosome III that is necessary for directionality. The chromatin structure of this region differs strikingly in a- and alpha-cells. Mat alpha2p organizes a 3.7 kb chromatin domain that opposes interaction of trans-acting proteins with the enhancer. In a-cells lacking the alpha2 repressor, two footprinted regions flank an approximately 100 bp section having a unique DNA structure. This structural signature probably reflects interactions of proteins that result in directional mating type switching. |
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