Isolation and Partial Characterization of Novel, Structurally Uniform (Hfq) Assemblies Carrying Accessory Transcription and Translation Factors.

In growing cells, the transcription-translation complexes (TTCs) form characteristic foci; however, the exact molecular composition of these superstructures is not known with certainty. Herein, we report that, during our recently developed "fast" procedures for purification of RNA polymerase (RP), a fraction of the RP's α/RpoA subunits is displaced from the core RP complexes and copurifies with multiprotein superstructures carrying the nucleic acid-binding protein Hfq and the ribosomal protein S6. We show that the main components of these large multiprotein assemblies are fixed protein copy-number (Hfq) complexes; these complexes have a high level of structural uniformity and are distinctly unlike the previously described (Hfq) "head-to-tail" polymers.