Regulation of the ECF sigma factor SigT by Lon-mediated proteolysis

• The Lon protease is widely conserved in both prokaryotic and eukaryotic species in which it fulfils important regulatory functions. Nevertheless, the number of identified Lon substrates is limited in most organisms and the precise role of Lon in regulating these proteins poorly understood. Previous quantitative proteomics data classified the general stress response sigma factor SigT as a promising putative Lon substrate in the dimorphic bacterium Caulobacter crescentus. Here, we confirm that SigT abundance is directly regulated by Lon. We show that downregulation of SigT levels during recovery from sucrose-induced osmotic stress is delayed in the absence of Lon, while its upregulation at the onset of stress functions normally. Furthermore, the presence of the Lon regulator LarA enhances Lon-mediated degradation of SigT in vitro and reduces SigT levels in vivo indicating a role of LarA in regulating Lon-mediated degradation of SigT. Together, our results emphasize the importance of Lon during the recovery phase following stress exposure by adjusting the concentration of the general stress response regulator SigT.

Subject headings

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Keyword

Lon protease

stress response

ECF sigma factor

proteolysis

molekylärbiologi

Molecular Biology

molekylär biovetenskap

Molecular Bioscience

molekylärbiologi

Molecular Biology

Publication and Content Type

vet (subject category)

ovr (subject category)