RskA Is a Dual Function Activator-Inhibitor That Controls SigK Activity Across Distinct Bacterial Genera

It has been previously shown that RskA, the anti-Sigma factor K of , inhibits SigK and that mutations in RskA promote high expression of the SigK regulon. The latter observation led us to hypothesize that RskA mutations lead to loss of the anti-Sigma factor function. In this report, we used natural...

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Bibliographic Details
Published in:Frontiers in microbiology 2020-09, Vol.11, p.558166-558166
Main Authors: Veyrier, Frédéric J, Nieves, Cecilia, Lefrancois, Louise H, Trigui, Hana, Vincent, Antony T, Behr, Marcel A
Format: Article
Language:English
Subjects:
anti-Sigma factor
Life Sciences
M. bovis
M. orygis
M. tuberculosis
Microbiology
Sigma factor K
Yersinia
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Summary:It has been previously shown that RskA, the anti-Sigma factor K of , inhibits SigK and that mutations in RskA promote high expression of the SigK regulon. The latter observation led us to hypothesize that RskA mutations lead to loss of the anti-Sigma factor function. In this report, we used natural and artificial mutations in RskA to determine the basis of the SigK-RskA partnership. Consistent with predictions, the N-terminal cytoplasmic portion of RskA was sufficient on its own to inhibit SigK. Unexpectedly, RskA also served as an activator of SigK. This activation depended on the same N-terminal region and was enhanced by the membrane-extracellular portion of RskA. Based on this, we engineered similar truncations in a Gram-negative bacterium, namely . Again, we observed that, with specific alterations of RskA, we were able to enhance SigK activity. Together these results support an alternative mechanism of anti-Sigma factor function, that we could term modulator (activator-inhibitor) in both and Gram-negative bacteria, suggesting that Sigma factor activation by anti-Sigma factors could be under-recognized.
ISSN:1664-302X
1664-302X
DOI:10.3389/fmicb.2020.558166