Proteomic and Phenotypic Analyses of a Putative YggS Family Pyridoxal Phosphate-Dependent Enzyme in Acidovorax citrulli

Abstract

<i>Acidovorax citrulli</i> (<i>Ac</i>) is a phytopathogenic bacterium that causes bacterial fruit blotch (BFB) in cucurbit crops, including watermelon. However, there are no effective methods to control this disease. YggS family pyridoxal phosphate-dependent enzyme acts as a coenzyme in all transamination reactions, but its function in <i>Ac</i> is poorly understood. Therefore, this study uses proteomic and phenotypic analyses to characterize the functions. The <i>Ac</i> strain lacking the YggS family pyridoxal phosphate-dependent enzyme, <i>AcΔyppAc</i>(EV), virulence was wholly eradicated in geminated seed inoculation and leaf infiltration. <i>AcΔyppAc</i>(EV) propagation was inhibited when exposed to L-homoserine but not pyridoxine. Wild-type and mutant growth were comparable in the liquid media but not in the solid media in the minimal condition. The comparative proteomic analysis revealed that YppAc is primarily involved in cell motility and wall/membrane/envelop biogenesis. In addition, <i>AcΔyppAc</i>(EV) reduced biofilm formation and twitching halo production, indicating that YppAc is involved in various cellular mechanisms and possesses pleiotropic effects. Therefore, this identified protein is a potential target for developing an efficient anti-virulence reagent to control BFB.

Revealing the Mechanism of Aroma Production Driven by High Salt Stress in Trichomonascus ciferrii WLW

“…Amino acids are known to be important for resistance to salt stress [ 37 ]. One of these membrane protein genes is the pyridoxal phosphate synthase subunit gene pdxS ( Figure 3 D), which is a cofactor for amino acid catabolic enzymes in the pyridoxal phosphate metabolism and is involved in amino acid catabolic reactions, such as transamination and decarboxylation [ 38 ]. In the present study, pdxS was significantly downregulated at the transcriptional level at Days 2–6, which is similar to previously reported results [ 39 ].…”

A putative glucose 6-phosphate isomerase has pleiotropic functions on virulence and other mechanisms in Acidovorax citrulli

“…To select the knockout mutant, the Tn5-insertional mutant library generated by EZ-Tn5 ™ <R6Kgori/KAN-2> Insertion Kit (Lucigen, Middleton, WI, USA) was screened as described previously (Lee et al, 2022b;Heo et al, 2023). After selecting a virulence-deficient mutant, the gene interrupted by Tn5 was identified using the manufacturer's protocol.…”

“…A label-free proteomic analysis was carried out using previously established protocols (Lee et al, 2022a;Heo et al, 2023). Ac and gpiAc: Tn5 strains with three biological replicates (6 samples) were used for the comparative analysis.…”

“…In addition, type II secretion system, type III secretion system, and quorum sensing have been identified as major virulence factors (Wang et al, 2016;Zivanovic and Walcott, 2017;Zhang et al, 2018;Kan et al, 2023). It is also reported that the ferric uptake regulator, YggS family pyridoxal phosphate-dependent enzymes, pyridoxal phosphate-dependent aminotransferases, glycerol-3-phosphate dehydrogenases, and 2, 3-bisphosphoglyceratedependent phosphoglycerate mutases, and the nitrogen regulator are associated with virulence in Ac (Liu et al, 2019;Kim et al, 2021;Lee et al, 2021;Lee et al, 2022b;Wang et al, 2022;Heo et al, 2023;Liu et al, 2023). However, these well-characterized factors/mechanisms involved are insufficient to comprehensively understand the virulence mechanisms of Ac.…”