SUNY at Albany
June 19-23, 2001
The solution structure of the Holliday Junction and other branched nucleic acids: Identification of Sequence Features that determine Conformer Selection
Branched nucleic acids play important roles in the living cell and its parasites. The Holliday junction, a four-way junction, is the central intermediate in both homologous and site-specific recombination. Three-way junctions are a recurring motif in RNA and arise in DNA during recombination and replication involving phages and viruses. Proteins that recognize their targets structure-specifically interact with these branched nucleic acids. Three-way and four-way junctions can undergo a folding process that is dependent on the local sequence around the junction and on the ionic strength of the solution.
We will present high-resolution solution structures of the Holliday junction as well as of DNA three-way junction(s) (1,2). These structures were derived in part using novel NMR methodology (3). We present experimental and theoretical structural data on the multi-valent ion binding to these and other junctions (4,5). The structural data of these and other junctions have been analyzed in detail. The sequence features which determine conformation selection have been identified. For DNA three-way junctions the conformer can now reliably be predicted based on the sequence around the junction. The Holliday junction structure provides insights into how proteins can recognize these entities in a structure-specific manner.References and and Footnotes
Bernd van Buuren, Juergen Schleucher, and Sybren Wijmenga
Department of medical Biosciences, Medical Biophysics, Umea University, S 90 187 Umea, Sweden