From this paper
However, based on the strong interaction between NusA and RNAP, we propose that the chaperone activity of NusA could provide more direct and concentrated protection for RNAP under stress, i.e., NusA could simultaneously act as a latent protector of RNAP during transcription elongation and termination.
By "protection" the authors mean that in the presence of NusA, some proteins are less prone to aggregation after heat shock. "Protection", in general, could also refer to stabilization i.e. reduction in the degradation rates of the protein.
To detect the influence of NusA on heat-induced aggregation, we used lactate dehydrogenase (LDH). LDH was incubated at 48°C in the absence or presence of NusA. As shown in Fig. 2b, LDH slowly aggregated at 48°C without the protection of NusA. However, when this experiment was performed in the presence of NusA, aggregation was visibly reduced. These results suggest that NusA also protects unfolded proteins from irreversible aggregation during thermal stress.
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In E. coli, RpoA and RpoB, the major components of RNAP, are prone to aggregation under heat stress in vivo. They were reported to interact with GroEL and DnaK, mainly for the protection from aggregation or refolding into a nonnative state48,49. However, based on the strong interaction between NusA and RNAP, we propose that the chaperone activity of NusA could provide more direct and concentrated protection for RNAP under stress, i.e., NusA could simultaneously act as a latent protector of RNAP during transcription elongation and termination.
