RNA polymerases from gram-positive and gram-negative bacteria differ in the presence or absence of additional subunits interacting with the core enzyme. One of these proteins is the delta subunit of gram-positive bacteria. The delta subunit was found to be associated with RNA polymerase of Bacillus subtilis almost 30 years ago, but its structure and function remains unknown. Recent reports indicating the importance of the delta subunit for the virulence of Staphylococcus aureus and Streptococcus agalactiae make the delta subunit interesting from the medical point of view. Aim of the project is to characterize structure and molecular motions of the delta subunit using nuclear magnetic resonance (NMR). In order to study the protein, various constructs labeled with isotopes N-15 and C-13 will be produced. Resonance frequencies of the backbone and of the side-chains will be assigned using a set of standard triple resonance experiments, HCCH-TOCSY, and N-15 and C-13 edited NOESY spectra. As the circular dichroism spectra indicated that the delta subunit is partially disordered, non-standard experiments with the C-13 detection may be needed to achieve sufficient resolution. Structural data such as NOE intensities will be obtained from the spectra and used as restraints in the 3D structure calculations. N-15 relaxation measurements will be performed and the data will be interpreted in terms of the spectral density functions and motional parameters such as correlation times and order parameters. The results will be used in the studies of interactions of the delta subunit with other proteins. The delta RNA polymerase subunit will be studied in cooperation with the group of Dr. L. Krásný (Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic).