Distinctive features of the Gac‐Rsm pathway in plant‐associated Pseudomonas

Abstract

This review focuses on the Gac-Rsm global regulatory pathway of plant-associated Pseudomonas from a novel perspective, analysing its differences and similarities between beneficial and phytopathogenic species and its role in plant interaction and colonization. Some technical considerations to approach the study of this system together with the questions that remain to be solved are also discussed.This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as

Compensatory mutations reducing the fitness cost of plasmid carriage occur in plant rhizosphere communities

“…Intriguingly, although deletion of PFLU4242 had no fitness effect in the absence of plasmids, deletion of gacS was beneficial in the absence of plasmids in competition with SBW25 (SBW25ΔgacS vs SBW25: t = 3.559, p = 0.0102). In line with previous studies of plant-associated Pseudomonas [31], this suggests that the Gac regulon is expressed by SBW25 on plants, that this expression is costly, but that non-responsive gacS mutants growing alongside wild-type cells may benefit from their Gac-regulated products.…”

Plasmid manipulation of bacterial behaviour through translational regulatory crosstalk

“…The mechanistic consequences of RsmQ/A/I heterodimerisation are currently unknown. The simplest explanation is that the three Rsm proteins are functionally and mechanistically interchangeable, and Rsm heterodimers have no in vivo function, however this seems unlikely given their distinct regulons (18). Alternatively, RsmQ may have an agonistic or antagonistic effect on the host Rsm proteins, increasing or reducing their RNA binding affinity.…”

“…The Gac-Rsm pathway is one of the best characterised translational regulatory systems in pseudomonads (10)(11)(12)(13)(14) and controls a wide variety of traits including biofilm formation (15), motility (16), quorum sensing (17), siderophore production (18) and virulence (8,19). Gac-Rsm is highly conserved within the Pseudomonas genus and comparable systems exist in a wide range of bacteria (8,14,18,20,21). Rsms are small (9 kDa) proteins that are able to interact directly with the bases AnGGA around the ribosome binding site (RBS) of their target transcript (21)(22)(23)(24).…”

“…It is currently unknown whether conjugative plasmids are able to manipulate translational regulatory pathways. The Gac-Rsm pathway is one of the best characterised translational regulatory systems in pseudomonads (10–14) and controls a wide variety of traits including biofilm formation (15), motility (16), quorum sensing (17), siderophore production (18) and virulence (8, 19). Gac-Rsm is highly conserved within the Pseudomonas genus and comparable systems exist in a wide range of bacteria (8, 14, 18, 20, 21).…”

RsmA3 modulates RpoS through the RetS‐Gac‐Rsm signalling pathway in response to H2O2 stress in the phytopathogen Pseudomonas syringae

“…In Pst DC3000, RsmA3 plays a major role in modulating the stress response for survival, while RsmA2 might play a minor role (Liu et al, 2021). Although the main components of the RetS‐Gac‐Rsm regulatory system are similar throughout the Pseudomonas genus, the regulatory mechanisms may differ (Ferreiro & Gallegos, 2021). A better understanding of the regulatory mechanism of oxidative tolerance and whether RpoS is the intermediate protein in the RetS‐GacS/A‐Rsm‐controlled expression of antioxidant genes in P .…”