Publications by authors named "Paul Dahlgren"
Background: Huntington's disease is an autosomal dominant progressive neurodegenerative disease associated with dramatic expansion of a polyglutamine sequence in exon 1 of the huntingtin protein htt that leads to cytoplasmic, and even nuclear aggregation of fibrils.
Methods: We have studied the in vitro fibril formation of mutant exon 1, and the shorter wild-type exon 1, with use of atomic force microscopy (AFM).
Results: Large aggregates are formed spontaneously after cleavage of the glutathione-S-transferase fusion protein of the mutant exon 1 protein.
Article Synopsis
- DNA looping regulates gene transcription in prokaryotes and eukaryotes, exemplified by the negative regulation of the gal operon in E. coli by Gal repressosome assembly involving GalR proteins and DNA looping.
- The formation of a 113 bp DNA loop is influenced by negatively supercoiled DNA and the histone-like protein HU, supporting a hypothesis of mutual antiparallel orientation of the gal operators.
- Atomic force microscopy confirmed this loop formation and indicated similarities to lac operator loops, while revealing that GalR can still repress the gal operon even in the absence of HU, prompting considerations of DNA structural organization in bacterial nucleoid.
Atomic force microscopy (AFM) was applied to directly visualize the end-to-end DNA interaction mediated by magnesium cations. We took advantage of the APS-mica, allowing the preparation of samples in a broad range of monovalent and divalent cations to separate the effects of Mg(2+) and Na(+) cations on the interaction of restriction DNA fragments with cohesive end. The AFM data clearly show that DNA restriction fragments with cohesive ends form substantial amount of circles in the presence of Mg(2+) cations, suggesting that Mg(2+) cations stabilize the interaction of cohesive ends.
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