As measurements of structure and dynamics become more and more important to analyze molecular machines in atomic detail, NMR spectroscopy emerges as a method of choice. Improved NMR techniques like TROSY-type (transverse relaxation optimized spectroscopy) experiments along with improved 2H-, 13C-, and 15N-labeling schemes and in combination with the usage of special precursors for specific labeling methyl groups, enable NMR to circumvent the problem of fast transversal relaxation, that otherwise leads to insufficient magnetization transfer for protein and their complexes above 25 kDa. These advances enabled the characterization of large protein complexes with sizes of several hundred kDa by NMR. Here, I propose to use and further develop advanced NMR techniques to solve the solution structure and study the function of a large protein complex, the homohexameric transcription termination factor Rho. Rho is an essential protein and plays important roles within transcription regulation and chromosome maintenance. In particular, Rho plays a significant role for transcription regulation in bacteria, because it controls the compliance of operon borders and defends the cell for horizontally derived DNA. Crystal structures of different functional states of Rho are available, and these can partly explain Rho’s inherent ATP-dependent translocase function. This translocase function enables Rho to bind and to move along RNA, leading to transcription termination by a direct interaction with the RNA Polymerase (RNAP) to dissociate it from the DNA. At the moment a description of Rho’s dynamics and the structural conversions accompanying its different states remains elusive, therefore I want to address these key aspects of Rho function with the following objectives: 1. Characterization of the structure and dynamics of the apo-form of Rho. 2. Structural and functional characterization of the Rho–rut-RNA interaction. 3. Structural and functional characterization of the interaction between Rho and its co-factor NusG.