SCIENCE AT THE EDGE SEMINAR

Friday, 15 April 2011 at 11:30am

Room 1400 Biomedical and Physical Sciences Bldg.

Refreshments at 11:15

** POSTPONED FROM FEBRUARY 25TH, 2011 **

Speaker: Hashim M. Al-Hashimi
         Department of Chemistry and Biophysics, University of Michigan

Title:   The Nucleic Acid Dance at Atomic-Resolution

Abstract:

NMR data and computational molecular dynamics simulations are combined to
yield a 3D atomic view of thermal fluctuations in nucleic acids over
timescales spanning picoseconds to milliseconds.  Detailed analysis of RNA
dynamic trajectories reveals spatially choreographed movements within a
pre-confined space in which helices linked by two-way junctions twist in a
synchronized manner while simultaneously bending. The spatial choreography
of the dynamics is a universal and fundamental feature of RNA structure,
which arises from topological constraints encoded at the secondary structure
level. A combined NMR-computational analysis reveals that simple DNA duplexes
undergo excursions outside the Watson-Crick framework towards Hoogsteen base
pairs that are transiently (<1%) sampled ubiquitously across all CA steps at
slow micro-to-millisecond timescales. The observation of Hoogsteen base pairs
in duplex DNAs bound to proteins and in the context of damaged DNA suggest
that DNA sequences code for excited-state structures that could provide yet
another layer of genetic information.