Inferring the Significance of the Polyamine Metabolism in the Phytopathogenic Bacteria Pseudomonas syringae: A Meta-Analysis Approach

Abstract

To succeed in plant invasion, phytopathogenic bacteria rely on virulence mechanisms to subvert plant immunity and create favorable conditions for growth. This process requires a precise regulation in the production of important proteins and metabolites. Among them, the family of compounds known as polyamines have attracted considerable attention as they are involved in important cellular processes, but it is not known yet how phytopathogenic bacteria regulate polyamine homeostasis in the plant environment. In the present study, we performed a meta-analysis of publicly available transcriptomic data from experiments conducted on bacteria to begin delving into this topic and better understand the regulation of polyamine metabolism and its links to pathogenicity. We focused our research on Pseudomonas syringae, an important phytopathogen that causes disease in many economically valuable plant species. Our analysis discovered that polyamine synthesis, as well as general gene expression activation and energy production are induced in the early stages of the disease. On the contrary, synthesis of these compounds is inhibited whereas its transport is upregulated later in the process, which correlates with the induction of virulence genes and the metabolism of nitrogen and carboxylic acids. We also found that activation of plant defense mechanisms affects bacterial polyamine synthesis to some extent, which could reduce bacterial cell fitness in the plant environment. Furthermore, data suggest that a proper bacterial response to oxidative conditions requires a decrease in polyamine production. The implications of these findings are discussed.

Polyamine-mediated mechanisms contribute to oxidative stress tolerance in Pseudomonas syringae

“…Altogether, we have shown that exposure to oxidative stress results in an increase in the concentration of extracellular Put in P. syringae. Besides, we demonstrated that perturbing the synthesis of Spd promotes oxidative stress tolerance, which correlates with our previous report describing the downregulation of Spd synthesis as a response to H 2 O 2 in several bacterial species 18 . This is associated to the stabilization of the outer membrane and the induction of catalases (Fig.…”

“…Therefore, the existence of a regulatory mechanism where Spd functions as a negative modulator of catalase activity could explain the reason behind the stress tolerant phenotype observed in the ∆speE strain. In this trend, our previous co-expression analyses on several P. syringae strains demonstrated a negative correlation between polyamine biosynthetic genes and catalases 18 . Besides, it was demonstrated that speE is downregulated in P. syringae B728A and P. aeruginosa PAO1, as well as in non-related species such as E. coli and Salmonella enterica in response to H 2 O 2 48,[56][57][58] .…”

Transcriptome profiling of type VI secretion system core gene tssM mutant of Xanthomonas perforans highlights regulators controlling diverse functions ranging from virulence to metabolism

“…At low concentration of zinc, the Zur regulator induces the expression of ZnuABC and activates T6SS genes ( 86 ). Breakdown of arginine by catabolic enzymes (SpeA and AguA) produces putrescine, exported out of the cell by transporters (PotABC) and helps in ROS scavenging ( 87 ).…”

Transcriptome profiling of type VI secretion system core genetssMmutant ofXanthomonas perforanshighlights regulators controlling diverse functions ranging from virulence to metabolism

“…At low concentration of zinc, the Zur regulator induces the expression of ZnuABC and activates T6SS genes (79). Breakdown of arginine by catabolic enzymes (SpeA and AguA) produce putrescine, exported out of the cell by transporters (PotABC) and helps in ROS scavenging (80).…”