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Dual role of a (p)ppGpp‐ and (p)ppApp‐degrading enzyme in biofilm formation and interbacterial antagonism
Author(s) -
Steinchen Wieland,
Ahmad Shehryar,
Valentini Martina,
Eilers Kira,
Majkini Mohamad,
Altegoer Florian,
Lechner Marcus,
Filloux Alain,
Whitney John C.,
Bange Gert
Publication year - 2021
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14684
Subject(s) - biology , biofilm , hydrolase , enzyme , biochemistry , guanosine , microbiology and biotechnology , pseudomonas aeruginosa , effector , stringent response , type vi secretion system , antagonism , nucleotide , bacteria , genetics , mutant , gene , receptor , virulence
The guanosine nucleotide‐based second messengers ppGpp and pppGpp (collectively: (p)ppGpp) enable adaptation of microorganisms to environmental changes and stress conditions. In contrast, the closely related adenosine nucleotides (p)ppApp are involved in type VI secretion system (T6SS)‐mediated killing during bacterial competition. Long R elA‐ S poT H omolog (RSH) enzymes regulate synthesis and degradation of (p)ppGpp (and potentially also (p)ppApp) through their synthetase and hydrolase domains, respectively. S mall a larmone h ydrolases (SAH) that consist of only a hydrolase domain are found in a variety of bacterial species, including the opportunistic human pathogen Pseudomonas aeruginosa . Here, we present the structure and mechanism of P. aeruginosa SAH showing that the enzyme promiscuously hydrolyses (p)ppGpp and (p)ppApp in a strictly manganese‐dependent manner. While being dispensable for P. aeruginosa growth or swimming, swarming, and twitching motilities, its enzymatic activity is required for biofilm formation. Moreover, (p)ppApp‐degradation by SAH provides protection against the T6SS (p)ppApp synthetase effector Tas1, suggesting that SAH enzymes can also serve as defense proteins during interbacterial competition.