Localized Recombination Drives Diversification of Killing Spectra for Phage Derived Syringacins

Abstract

To better understand the potential for detrimental interactions between strains of the same bacterial species, we have surveyed bacteriocin killing activity across a diverse suite of strains of the phytopathogen Pseudomonas syringae. Our data demonstrate that killing activity from phage derived bacteriocins of P. syringae (R-type syringacins) is widespread. Despite a high overall diversity of bacteriocin activity, strains can broadly be classified into five main killing types and two main sensitivity types. Furthermore, we show that killing activity switches frequently between strains, and that switches correlate with localized recombination of two genes that together encode the proteins that specify bacteriocin targeting. Lastly, we demonstrate that phage derived bacteriocin killing activity can be swapped between strains simply through expression of these two genes in trans. Overall, our study characterizes extensive diversity of killing activity for phage derived bacteriocins of P. syringae across strains and highlights the power of localized recombination to alter phenotypes that mediate strain interactions during evolution of natural populations and communities.

Variation at the common polysaccharide antigen locus drives lipopolysaccharide diversity within the Pseudomonas syringae species complex

“…While this study is unlikely to be an exhaustive identification of TET operon variants, a significant proportion of available P. syringae whole genome sequences . Hierarchical clustering analysis using the ward.D2 method was used to build a tailocin sensitivity phylogeny from the sensitivity matrix provided in the study by Baltrus et al (2019), which is transposed from a syringacin killing matrix. The TET operon phylogeny was produced by using the TET operon genome sequences of selected strains, assembled into a phylogeny using the UPGMA clustering method, as was the MLST phylogeny.…”

A Moving Target: The Megaplasmid pMPPla107 Sensitizes Cells to an Inhibitory Agent Conserved AcrossPseudomonas spp

“…Bacteria exist in complex ecological networks where interactions between community members range from mutualistic to antagonistic. Individual strains have therefore developed a variety of methods to interact with and/or outcompete surrounding bacterial cells including the production of secondary metabolites that can inhibit or allow growth of various microorganisms, as well as bacteriocins that kill target cells with high specificity (1)(2)(3)(4)(5)(6)(7)(8)(9). Secondary metabolites can also provide neighboring microbes a previously missing metabolic resource allowing for colonization of previously uninhabitable niches (10,11).…”

Variation at the common polysaccharide antigen locus drives lipopolysaccharide diversity within theP. syringaespecies complex

“…Interestingly, the range of molecular weights of 311 different LPS molecules within clades was highly variable, suggesting the efficiency 317 Like phages, many R-type syringacins (tailocins) use LPS as a receptor. Recently 318 the R-syringacin killing and sensitivity spectra for a diverse range of P. syringae 319 isolates were characterised (Baltrus et al, 2019). A feature of both spectra is that 320 dendrograms generated from the killing and sensitivity matrices do not match MLST 321 phylogenetic trees (Baltrus et al, 2019).…”

“…Recently 318 the R-syringacin killing and sensitivity spectra for a diverse range of P. syringae 319 isolates were characterised (Baltrus et al, 2019). A feature of both spectra is that 320 dendrograms generated from the killing and sensitivity matrices do not match MLST 321 phylogenetic trees (Baltrus et al, 2019). Since LPS is a likely receptor for R-322 syringacins, we hypothesised that there might be a correlation between the patterns 323 of variation in tailocin sensitivity within P. syringae isolates and the genetic variation 324 in the TET operon responsible for the structure of the CPA backbone.…”

“…This has been 391 responsible for generation of the 78 immunologically distinct capsule variants which 392 have been described in K. pneumoniae(Wyres et al, 2015).393 Tailocins are a subset of bacteriocins derived from phage tail proteins that394 have been co-opted by host bacteria as a means for killing closely related bacterial 395 isolates occupying the same ecological niche(Ghequire and De Mot, 2015). What 396 has been demonstrated recently within P. syringae is the depth and complexity of 397 both the killing and sensitivity spectra generated from a wide range of isolates 398(Baltrus et al, 2019). While it is clear that LPS is a receptor for some tailocins, a link 399 between the sensitivity to tailocins and the structural variation in LPS has not been 400 demonstrated until now.…”