Investigation of the Role of a Zinc Uptake Regulator (Zur) in the Virulence of Pectobacterium odoriferum

Functional investigation of Zur in metal ion homeostasis, motility and multiple stresses resistance in cyanobacteria Synechocystis sp. PCC 6803

Zur (zinc uptake regulator), a member of the Fur (ferric uptake regulator) family of transcriptional regulators, plays multifaceted roles by regulating the gene expressions, such as modulating zinc ion uptake by regulating the znuABC gene cluster and influencing bacterial motility by modulating genes associated with flagella or pili. The photosynthetic autotroph Synechocystis sp. PCC 6803 is frequently used as an indicator organism for water pollution and a cell factory for high-value biochemical production in synthetic biology. During its growth, this organism often encounters various abiotic stresses, including oxidative, salt, and antibiotic stress. In this study, we conducted transcriptomic analysis on both Δzur mutant and wild-type (WT) strains to identify potential Zur-regulated genes in Synechocystis sp. PCC 6803. These genes primarily participate in multiple pathways such as inorganic ion transport, carbohydrate transport, energy production and conversion, and cell motility. Zur not only controls zinc ion homeostasis within the cell but also influences the iron balance by directly regulating the expression of the fur gene. In terms of motility, Zur regulates the expression of bacterial pili gene cluster and other motility-related genes, thereby affecting the twitching motility of Synechocystis sp. PCC 6803. Furthermore, Zur plays a crucial role in promoting biofilm formation and enhancing resistance to salt, oxidative, and antibiotic stresses by modulating relative gene expression. In conclusion, as a global transcriptional regulator, Zur plays pivotal roles in metal ion homeostasis, motility, and resistance to multiple stresses in Synechocystis sp. PCC 6803. This study illustrates the Zur regulons in Synechocystis sp. PCC 6803, and underscores the importance of Zur in enhancing the environmental adaptability of cyanobacteria.

Functional versatility of Zur in metal homeostasis, motility, biofilm formation, and stress resistance in Yersinia pseudotuberculosis

Zur (zinc uptake regulator) is a significant member of the Fur (ferric uptake regulator) superfamily, which is widely distributed in bacteria. Zur plays crucial roles in zinc homeostasis and influences cell development and environmental adaptation in various species. Yersinia pseudotuberculosis is a Gram-negative enteric that pathogen usually serves as a model organism in pathogenicity studies. The regulatory effects of Zur on the zinc transporter ZnuABC and the protein secretion system T6SS have been documented in Y. pseudotuberculosis. In this study, a comparative transcriptomics analysis between a ∆zur mutant and the wild-type (WT) strain of Y. pseudotuberculosis was conducted using RNA-seq. This analysis revealed global regulation by Zur across multiple functional categories, including membrane transport, cell motility, and molecular and energy metabolism. Additionally, Zur mediates the homeostasis not only of zinc but also ferric and magnesium in vivo. There was a notable decrease in 35 flagellar biosynthesis and assembly-related genes, leading to reduced swimming motility in the ∆zur mutant strain. Furthermore, Zur upregulated multiple simple sugar and oligopeptide transport system genes by directly binding to their promoters. The absence of Zur inhibited biofilm formation as well as reduced resistance to chloramphenicol and acidic stress. This study illustrates the comprehensive regulatory functions of Zur, emphasizing its importance in stress resistance and pathogenicity in Y. pseudotuberculosis.

IMPORTANCE

Bacteria encounter diverse stresses in the environment and possess essential regulators to modulate the expression of genes in responding to the stresses for better fitness and survival. Zur (zinc uptake regulator) plays a vital role in zinc homeostasis. Studies of Zur from multiple species reviewed that it influences cell development, stress resistance, and virulence of bacteria. Y. pseudotuberculosis is an enteric pathogen that serves a model organism in the study of pathogenicity, virulence factors, and mechanism of environmental adaptation. In this study, transcriptomics analysis of Zur's regulons was conducted in Y. pseudotuberculosis. The functions of Zur as a global regulator in metal homeostasis, motility, nutrient acquisition, glycan metabolism, and nucleotide metabolism, in turn, increasing the biofilm formation, stress resistance, and virulence were reviewed. The importance of Zur in environmental adaptation and pathogenicity of Y. pseudotuberculosis was emphasized.