Structure and mechanism of multicomponent protein-nucleic acid assemblies.

The research will focus on analysing protein-nucleic acid interactions in the framework of large assemblies. Although the main emphasis is on X-ray analysis, several complementary techniques such as electron microscopy, mass spectrometry, surface plasmon resonance, polarisation anisotropy and analytical ultracentrifugation, which provide insight into the assemblys composition and the strength of interaction, will be applied. Key goals: (1) To continue investigations into the mechanism of DNA t ranslocation by double-stranded DNA viruses, using motor proteins of several bacteriophages belonging to Siphoviridae. To characterise interactions between the large and small terminase proteins, portal protein and DNA. To analyse the three-dimensional organisation of the motor using a combination of X-ray structural analysis with electron microscopy. To understand how structural events associated with ATP hydrolysis are coupled with the mechanical translocation of DNA. (2) To understand the st ructure-function relationship for several tRNA modifying enzymes, with particular focus on human hDus2 protein linked with lung cancer. To characterize protein interactions with tRNA and determine the crystal structures of protein-tRNA complexes. (3) To use structural knowledge on the viral motor and other oligomeric assemblies for pilot studies aimed at engineering a stable molecular device that can be used for transfer of genetic information in a controlled fashion.