Modulation of the RNA polymerase activity by AtcB, a protein associated with a DnaK chaperone network in Shewanella oneidensis

Bacteria possess several molecular pathways to adapt to changing environments and to stress conditions. One of these pathways involves a complex network of chaperone proteins that together control proteostasis. In the aquatic bacterium Shewanella oneidensis, we have recently identified a previously unknown co-chaperone of the DnaK/Hsp70 chaperone system, AtcJ, that is essential for adaptation to low temperatures. AtcJ is encoded in the atcJABC operon, whose products, together with DnaK, form a protein network allowing growth at low temperature. However, how these proteins allow cold adaptation is unknown. Here, we found that AtcB directly interacts with the RNA polymerase and decreases its activity. In addition, AtcB overproduction prevents bacterial growth due to RNA polymerase inhibition. Together, these results suggest that the Atc proteins could direct the DnaK chaperone to the RNA polymerase to sustain life at low temperatures. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

Bacteria use molecular pathways and protein networks to adapt to changing environments and stress conditions, with one pathway involving the essential co-chaperone AtcJ in the DnaK/Hsp70 system for cold adaptation. AtcJ is part of the atcJABC operon, and it interacts with RNA polymerase to maintain life at low temperatures.