Solution structure of the N-terminal domain of Bacillus subtilis delta subunit of RNA polymerase and its classification based on structural homologs.

RNA polymerase is an essential multisubunit enzyme responsible for transcription of genetic information from DNA into RNA. The RNA polymerase from Bacillus subtilis differs from its analogue from gram-negative bacteria in a presence of two additional subunits, omega1 and delta. Their role in the transcription machinery is still not clear. In this study, we focused on the N-terminal part of delta subunit to reveal its structure. The sample was prepared using a standard protocol of overexpression in the E.coli system to produce a 15N,13C-uniformly labeled sample. A standard set of spectra was measured on a 600MHz spectrometer. The distance restrains were extracted and assigned from NOESY spectra. The additional RDC restraints and anisotropic contributions to the 13C chemical shifts were used in the final refinement. The quality of the calculated structures were checked. The determined structure was identified based on structure homology with some proteins from the Forkhead DNA-binding domain SCOP family.