W0432

Towards a Neutron Model for a Protein/DNA Interface. Catherine L. Lawson, Rutgers Univ., Dept. of Chemistry and Chemical Biology, 610 Taylor Rd., Piscataway, NJ 08854, lawson@rutchem.rutgers.edu.

The trp repressor/operator complex (Otwinowski et al., 1988) was the first structure determined by X-ray crystallography at sufficiently high resolution to observe the fine details of a protein/DNA interface. The structure identified ~53 solvent molecules mediating interactions between the protein dimer and DNA duplex. Included among these are waters that appear to mediate sequence-specific interactions between the protein and DNA through an extended network of hydrogen-bonds. Neutron diffraction studies of this system will yield more complete structural information about of the role of interfacial water in this macromolecular interaction. Preliminary neutron data for the uncomplexed protein have been obtained (Daniels et al, 2003); challenges towards realizing the goal of a neutron model for the full protein/DNA complex will be presented.

Otwinowski, Z., Schevitz, R.W., Zhang, R.G., Lawson, C.L., Joachimiak, A., Marmorstein, R.Q., Luisi, B.F., Sigler, P.B. Crystal structure of trprepressor/operator complex at atomic resolution. Nature 335, 321-9. (1988).

Daniels, B.V., Myles, D.A.A., Forsyth, V.T. & Lawson, C.L. Crystals of trp repressor suitable for high resolution neutron Laue diffraction studies. Acta Cryst D59, 136-138 (2003).