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CPP: Chemische Physik und Polymerphysik
CPP 17: Poster: Spectroscopy and Single Particle Spectroscopy of Molecular Systems, Photoprocesses, Biological Systems
CPP 17.22: Poster
Tuesday, April 3, 2001, 12:30–15:00, AT1
UV-light damaged DNA and its interaction with hsRPA: an atomic force microscopy study — •Marina Lysetska1, Daniel Boehringer2, Thomas Hey2, Gerhard Krauss2, and Georg Krausch1 — 1Physikalische Chemie II, Univesität Bayreuth, D-95440 Bayreuth — 2Biochemie, Universität Bayreuth, D-95440 Bayreuth
The human replication protein A (hsRPA) is an essential component of DNA replication and DNA repair multiprotein complexes. hRPA consists of three subunits of 70, 32 and 14 kDa and binds specifically to single stranded DNA and to damaged DNA. Since the discovery and description of hsRPA, a lot has been learned about its structure and function, but the different modes of RPA binding to single- and double- stranded DNA are still not understood. In the present work, we use AFM TappingMode imaging under physiological conditions to examine conformational changes related to the amount of DNA UV-damage and DNA-hsPRA complex formation. Double stranded DNA was exposed to UV-light to produce non-specifically damaged DNA. Complexes of damaged DNA with hsRPA were imaged in buffer. The complexes were immobilized via nickel ions onto freshly cleaved mica surface. We observed a complicated structure of the complex indicating that DNA wraps around the protein molecule. This finding can be attributed to the numerous binding sites on UV damaged DNA and more than a single binding site on the protein.