Lon protease negatively affects GacA protein stability and expression of the Gac/Rsm signal transduction pathway in Pseudomonas protegens. (18th February 2014)

• Record Type: Journal Article
• Authors: Takeuchi, Kasumi; Tsuchiya, Wataru; Noda, Naomi; Suzuki, Rintaro; Yamazaki, Toshimasa; Haas, Dieter
• Is Part Of: Environmental microbiology. Volume 16:Number 8(2014:Aug.)
• Page Start: 2538
• Page End: 2549
• Publication Date: 2014-02-18
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12394
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>In <italic>P</italic><italic>seudomonas protegens</italic> CHA0 and other fluorescent pseudomonads, the Gac/Rsm signal transduction pathway controls secondary metabolism and suppression of fungal root pathogens via the expression of regulatory small RNAs (sRNAs). Because of its high cost, this pathway needs to be protected from overexpression and to be turned off in response to environmental stress such as the lack of nutrients. However, little is known about its underlying molecular mechanisms. In this study, we demonstrated that Lon protease, a member of the ATP‐dependent protease family, negatively regulated the Gac/Rsm cascade. In a <italic>lon</italic> mutant, the steady‐state levels and the stability of the GacA protein were significantly elevated at the end of exponential growth. As a consequence, the expression of the sRNAs RsmY and RsmZ and that of dependent physiological functions such as antibiotic production were significantly enhanced. Biocontrol of <italic>P</italic><italic>ythium ultimum </italic>on cucumber roots required fewer <italic>lon </italic>mutant cells than wild‐type cells. In starved cells, the loss of Lon function prolonged the half‐life of the GacA protein. Thus, Lon protease is an important negative regulator of the Gac/Rsm signal transduction pathway in <italic>P</italic><italic>. protegens</italic>.</p> </abstract>