Pseudomonas aeruginosa PA14 produces R-bodies, extendable protein polymers with roles in host colonization and virulence

Abstract

R-bodies are long, extendable protein polymers formed in the cytoplasm of some bacteria; they are best known for their role in killing of paramecia by bacterial endosymbionts. Pseudomonas aeruginosa PA14, an opportunistic pathogen of diverse hosts, contains genes (referred to as the reb cluster) with potential to confer production of R-bodies and that have been implicated in virulence. Here, we show that products of the PA14 reb cluster associate with R-bodies and control stochastic expression of R-body structural genes. PA14 expresses reb genes during colonization of plant and nematode hosts, and R-body production is required for full virulence in nematodes. Analyses of nematode ribosome content and immune response indicate that P. aeruginosa R-bodies act via a mechanism involving ribosome cleavage and translational inhibition. Our observations provide insight into the biology of R-body production and its consequences during P. aeruginosa infection.

Systematic identification of molecular mediators of interspecies sensing in a community of two frequently coinfecting bacterial pathogens

“…Bacterial strains and plasmids are listed in S2 Table . Promoter sequences were amplified using the primers listed in S3 Table . The amplified fragments were cloned by Gibson Assembly (New England Biolabs) into SpeI-and XhoI-digested pSEK109 (pLB3208), provided by the Dietrich lab [106]. Plasmids were transformed into E. coli S17-1 λ-pir and confirmed by sequencing.…”

Novel evolutionary insights on the interactions of the Holosporales (Alphaproteobacteria) with eukaryotic hosts from comparative genomics

“…), or ‘ Caedimonas ’, which confers to its host a killer‐trait towards non‐infected conspecifics involving the peculiar proteinaceous R‐bodies (Schrallhammer et al, 2018). R‐bodies were also found in a number of phylogenetically unrelated non‐ Holosporales bacteria, with potential involvement in host interactions (Raymann et al, 2013; Schrallhammer & Schweikert, 2009; Wang et al, 2021), but, to our knowledge, until now never described in other Holosporales .…”

“…While inspecting the genes encoded in the Bealeia plasmids, some ORFs were found with homology to the reb genes, namely the determinants of R‐bodies in the Paramecium symbiont Caedibacter taeniospiralis (Schrallhammer & Schweikert, 2009) and in other bacteria (Wang et al, 2021). This finding was unexpected, as no R‐bodies were observed in ultrastructural investigations on Bealeia (Szokoli et al, 2016).…”

“…From this perspective, the reb genes, putatively encoding for the R‐bodies, are distinctive. R‐bodies are proteinaceous structures well known for being involved in the competitively advantageous killer trait conferred to Paramecium by Caedibacter or by the Holosporales bacterium ‘ Caedimonas ’ towards non‐infected conspecifics (Schrallhammer & Schweikert, 2009), and likely modulating interactions with eukaryotes in several other bacteria (Wang et al, 2021). Herein, we found reb genes also in Bealeia and in ‘ Ca .…”

“…For the phylogeny of the Reb proteins (components of R‐bodies), we started from the dataset by Wang et al (Wang et al, 2021). To minimize false negatives, each amino acid sequence from such dataset was queried on each Holosporales bacterium, and combined hits were manually inspected, thus selecting the putative Reb sequences.…”