Live cell dynamics of production, explosive release and killing activity of phage tail-like weapons for Pseudomonas kin exclusion

Abstract

Interference competition among bacteria requires a highly specialized, narrow-spectrum weaponry when targeting closely-related competitors while sparing individuals from the same clonal population. Here we investigated mechanisms by which environmentally important Pseudomonas bacteria with plant-beneficial activity perform kin interference competition. We show that killing between phylogenetically closely-related strains involves contractile phage tail-like devices called R-tailocins that puncture target cell membranes. Using live-cell imaging, we evidence that R-tailocins are produced at the cell center, transported to the cell poles and ejected by explosive cell lysis. This enables their dispersal over several tens of micrometers to reach targeted cells. We visualize R-tailocin-mediated competition dynamics between closely-related Pseudomonas strains at the single-cell level, both in non-induced condition and upon artificial induction. We document the fatal impact of cellular self-sacrifice coupled to deployment of phage tail-like weaponry in the microenvironment of kin bacterial competitors, emphasizing the necessity for microscale assessment of microbial competitions.

SOS-Independent Pyocin Production in P. aeruginosa Is Induced by XerC Recombinase Deficiency

“…More recently, a study in P. protegens examined fluorescent fusions to tailocins, which are similar to pyocins, to directly observe intraspecies killing. In that work, tailocin production was likewise observed to be heterogeneous ( 27 ). Building on this evidence, we thus hypothesized that pyocin expression would be heterogeneous, even when strongly induced by xerC deletion.…”

“…Such heterogeneity has been observed for colicin production by Escherichia coli ( 25 ) and has also been implicated in P. aeruginosa biofilms, where explosive lysis of a small subset of cells, mediated by the lysin gene of the R/F pyocin cluster, also functions to contribute extracellular DNA to biofilm communities ( 26 ). Microscopic observation of fluorescently tagged pyocin-like tailocins in Pseudomonas protegens also revealed heterogeneity in tailocin production ( 27 ). Similarly, P. aeruginosa virulence appears to benefit from the lysis of a subset of cells mediated by the Alp pathway.…”

Spatial transcriptomics of planktonic and sessile bacterial populations at single-cell resolution

“…In contrast, the expression of recA did not follow this pattern, suggesting a pyocin-specific effect (Figure 5G). Notably, a recent study discovered an identical polar localization for two different Pseudomonas protegens R-tailocins at the protein level (Vacheron et al, 2021). Together, these data hint at a potentially evolutionary conserved RNA-dependent mechanism for R-tailocin protein polar localization.…”

“…These elements are thought to be adapted from prophages and are applied as narrow-spectrum toxins for kin exclusion (Bobay et al, 2014;Ghequire and De Mot, 2015). However, in contrast with antibiotics, these phage taillike structures are released into the environment via explosive lysis events that kill the producer and spray the toxin locally to inhibit nearby competitors (Turnbull et al, 2016;Vacheron et al, 2021). This event also releases extracellular DNA that integrates into the biofilm matrix, structurally supporting biofilm maturation (Turnbull et al, 2016;Whitchurch et al, 2002).…”

A Lytic Yersina pestis Bacteriophage Obtained From the Bone Marrow of Marmota himalayana in a Plague-Focus Area in China

“…During infection by bacteria, TPPA can bind with bacterial receptors to mediate bacteriophage adsorption and subsequent bacterial lysis ( Hu et al., 2020 ; Pyra et al., 2020a ; Pyra et al., 2020b ). If differences occur specifically in the genes encoding the tail fibers, then recognition of the cell target will change ( Vacheron et al., 2021 ). How a mutation in the upstream activating sequence of TTPA modifies its expression merits investigation.…”