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AKB: Biologische Physik

AKB 50: Imaging and Microscopy

AKB 50.1: Vortrag

Montag, 7. März 2005, 16:00–16:15, TU H2013

FRET Studies of the Mobility of TBP-DNA Complexes upon Binding of NC2 — •Don C. Lamb^1,2,3, Peter Schlüsche^1,3, Christoph Bräuchle^1,3, Gertrard Stelzer⁴, and Michael Meisterernst⁴ — ¹Physical Chemistry, LMU Munich, Munich, Germany — ²Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA — ³Center for Nanoscience, LMU, Munich, Germany — ⁴National Research Center for Environment and Health, Munich, Germany

Transcription of DNA into RNA is an essential process in life and the initiation of the transcription processes is a popular target for gene regulation. Transcription is initiated with binding of the TATA box binding protein (TBP) to the promoter site on the DNA and recruiting other elements of the transcription complex. When negative cofactor 2 (NC2) is present, transcription is down regulated. NC2 binds to TBP with high affinity. Biochemical evidence suggests that upon binding, the TBP-NC2 complex diffuses along the DNA. Hence, transcription is down regulated because the TBP is not longer located at the promoter site. To verify this hypothesis and to investigate the mobility of the TBP-NC2 complex upon NC2 binding, we have performed fluorescence resonance energy transfer (FRET) experiments on single molecules. TBP was labeled specifically with a donor molecule while a short piece of double-stranded DNA containing a TATA box in the center was labeled with an acceptor. The FRET efficiency was measured before NC2 and after addition of NC2 to solution to investigate the dynamics of individual TBP-NC2 complexes.