Regensburg 2002 – scientific programme
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SYBM: Physik biologischer Materie
SYBM 401: Physics of biological matter: Poster
SYBM 401.33: Poster
Tuesday, March 12, 2002, 18:00–19:30, H37
AFM investigation of protein-DNA interactions — •M. Lysetska1, I. Oka1, G. Lipps2, T. Hey2, G. Krauss2, and G. Krausch1 — 1Physikalische Chemie II, Universität Bayreuth, 95440 Bayreuth, Germany — 2Laboratorium für Biochemie, Universität Bayreuth, 95440 Bayreuth, Germany
Atomic force microscopy was used to investigate the interaction of two different proteins (heterotrimer human replication protein A (RPA, subunits of 116 kDA) and DNA sequence dependant ORF80 (9.5 kDa) from Sulfolobus islandicus) with the same 538 bp DNA fragment. The DNA fragments contained two binding sites for ORF80, but AFM measurements show low affinity of the ORF80 to the DNA under the experimental conditions. Only about half of the DNA molecules formed complexes with one or two protein molecules. As S. islandicusis a thermophil microorganism, we studied the ORF80 binding properties at various temperatures.
AFM investigation of RPA (Stokes radius 5 nm) shows only random cases of terminal binding to intact DNA molecules. After UV irradiation, however, DNA fragments form complexes with the human RPA. AFM reveals conformational changes related to the complex formation of intact and UV damaged DNA with RPA. The DNA molecules seem to No-dqwrapNo-dq around the RPA, which in turn results in a considerable reduction of its apparent contour length.