Burkholderia gladioli strain NGJ1 deploys a prophage tail-like protein for mycophagy

Abstract

Fungal pathogens are responsible for approximately two third of the infectious plant diseases. Historically they have been associated with several devastating famines, causing death and disabilities in humans. Mostly fungal diseases are being controlled by using fungicides which otherwise have adverse side effects on the health of consumers as well as environment. Due to extensive usages, pathogens have evolved resistance against most of the commonly used fungicides and rendered them ineffective. Controlling fungal disease in a sustainable and eco-friendly fashion remains a challenge. The antifungal biocontrol agents are being considered as potent, alternative and ecofriendly approach to manage fungal diseases. In our recent work, we have identified a rice associated bacterium; Burkholderia gladioli strain NGJ1 which demonstrates broad spectrum fungal eating (mycophagous) property. We determined that the bacterium utilizes its type III secretion system (Injectisome) machinery to deploy a prophage tail-like protein (Bg_9562) into fungal cells to devour them. The purified Bg_9562 protein from overexpressing recombinant E. coli strain demonstrates broad spectrum antifungal activity. Overall our study opens up a new opportunity to exploit prophage taillike protein as potent antifungal compound to control plant as well as animal fungal diseases.

Global diversity and distribution of prophages are lineage-specific within the Ralstonia solanacearum plant pathogenic bacterium species complex

“…While prophages are known to affect plant pathogen fitness by mediating host growth, competitiveness, and virulence (29)(30)(31)(32)(33)(34)(35)(36)(37)41,80), only very little is known about their diversity and distribution at the pangenome-level. In this study, we analysed the prophage content of the plant pathogenic R. solanacearum bacterium using a representative, global collection of new 192 draft genome assemblies.…”

“…For example, prophages of some of the most destructive plant pathogens including Pseudomonas (26), Xylella (27), and Xanthomonas (28) spp., have been associated with auxiliary genes that encode plant immune response inhibitors (29,30), secretion system proteins, degradative enzymes, and toxin exporters (31)(32)(33). Plant pathogen competitiveness can also be mediated by prophages that encode competitor-repressing bacteriocins (34), provide resistance to environmental stresses such as toxic metal ions (35) and antimicrobials (36), or encourage survival during nutrient scarcity by increasing metabolic potential (37). However, the distribution, diversity, and functional potential of prophages is still relatively understudied at the pangenome-level with plant pathogenic bacteria.…”

Global diversity and distribution of prophages are lineage-specific within the Ralstonia solanacearum species complex

“…For example, prophages of some of the most destructive plant pathogens including Pseudomonas [ 23 ], Xylella [ 24 ], and Xanthomonas [ 25 ] spp., have been associated with auxiliary genes that encode plant immune response inhibitors [ 26 , 27 ], secretion system proteins, degradative enzymes, and toxin exporters [ 28 , 29 , 30 ]. Plant pathogen competitiveness can also be mediated by prophages that encode competitor-repressing bacteriocins [ 31 ], provide resistance to environmental stresses such as toxic metal ions [ 32 ] and antimicrobials [ 33 ], or encourage survival during nutrient scarcity by increasing metabolic potential [ 34 ]. However, the distribution, diversity, and functional potential of prophages are still relatively understudied at the pangenome-level with plant pathogenic bacteria.…”

The alternative sigma factors, rpoN1 and rpoN2 are required for mycophagous activity of Burkholderia gladioli strain NGJ1

“…Mycophagous bacteria can potentially serve as a better biocontrol agent, as they not only kill the pathogenic fungi but also utilize the fungal biomass. We have previously proposed that mycophagy is an important attribute of the bacterium to utilize co‐habiting fungi as a nutrient source and sustain growth under nutrient‐limiting conditions, without adversely affecting the host plant (Kumar et al ., 2018a). However, lysis of fungal cells elicited during mycophagy leads to release of fungal metabolites into extracellular milieu, making them accessible to various co‐habiting microbes.…”

“…The ClustalOmega (http://www.ebi.ac.uk/Tools/msa/clustalo/) (Sievers et al ., 2011) was used to align amino acid sequences of RpoN orthologues of different bacteria, while NCBI conserved domain database (http://www.ncbi.nlm.nih.gov/Structure/cdd/wrpsb.cgi/) was used to identify the conserved domains. The amino acid sequences of different RpoN orthologues were used to construct phylogenetic tree by Neighbour Joining using MEGAX (Kumar et al ., 2018b). The webFlaGs tool (Saha et al ., 2021) was used to study the gene neighbourhood of rpoN1 and rpoN2 genes, as described (Yadav et al ., 2021).…”