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<p>The σ<sup>54</sup> factor (RpoN), a significant&#xa0;transcriptional regulatory factor, plays crucial roles in regulating virulence, motility, biofilm formation, and the utilization of carbon and nitrogen sources in pathogenic bacteria. However, the function of RpoN has not been identified in <i>Paracidovorax citrulli</i> (formerly <i>Acidovorax citrulli</i>). To investigate this, we constructed a <i>rpoN1</i> deletion mutant and a corresponding complement strain in the background of <i>P. citrulli</i> strain xjl12. The <i>P. citrulli rpoN1</i> deletion mutant displayed attenuated virulence in melon. RNA-Seq analysis revealed that <i>rpoN1</i> is involved in regulating the expression of certain pathogenicity-associated genes related to the secretion system, biofilm formation, and motility. Phenotypic analysis demonstrated that the <i>rpoN1</i> deletion mutant of <i>P. citrulli</i> significantly attenuated biofilm formation, twitch motility, swarming motility, cotyledon colonization, and seed colonization. However, swimming motility was significantly enhanced in the <i>rpoN1</i> mutant. As expected, qRT-PCR assays indicated that the type IV pili-related gene <i>Aave_4679</i> (<i>pilA</i>) was barely expressed in the <i>rpoN1</i> mutant, and western blot analysis revealed that RpoN1 positively regulated the expression of <i>pilA</i>. Additionally, bacterial one-hybrid assays and electrophoretic mobility shift assays indicated that RpoN1 directly binds to the promoter of <i>pilA</i>. Our investigation revealed that RpoN1 is essential for the virulence of <i>P. citrulli</i> and provides valuable insights into the physiology and pathogenic mechanisms of bacterial fruit blotch.</p>

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RpoN1 (sigma factor 54) contributes to the virulence of Paracidovorax citrulli by regulating the expression of type IV pili PilA

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年3月13日

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  • Minghui Sun,
  • Yuqiang Zhao,
  • Liuyang Zhao,
  • Jun Wang,
  • Yanli Tian,
  • Baishi Hu

摘要

The σ54 factor (RpoN), a significant transcriptional regulatory factor, plays crucial roles in regulating virulence, motility, biofilm formation, and the utilization of carbon and nitrogen sources in pathogenic bacteria. However, the function of RpoN has not been identified in Paracidovorax citrulli (formerly Acidovorax citrulli). To investigate this, we constructed a rpoN1 deletion mutant and a corresponding complement strain in the background of P. citrulli strain xjl12. The P. citrulli rpoN1 deletion mutant displayed attenuated virulence in melon. RNA-Seq analysis revealed that rpoN1 is involved in regulating the expression of certain pathogenicity-associated genes related to the secretion system, biofilm formation, and motility. Phenotypic analysis demonstrated that the rpoN1 deletion mutant of P. citrulli significantly attenuated biofilm formation, twitch motility, swarming motility, cotyledon colonization, and seed colonization. However, swimming motility was significantly enhanced in the rpoN1 mutant. As expected, qRT-PCR assays indicated that the type IV pili-related gene Aave_4679 (pilA) was barely expressed in the rpoN1 mutant, and western blot analysis revealed that RpoN1 positively regulated the expression of pilA. Additionally, bacterial one-hybrid assays and electrophoretic mobility shift assays indicated that RpoN1 directly binds to the promoter of pilA. Our investigation revealed that RpoN1 is essential for the virulence of P. citrulli and provides valuable insights into the physiology and pathogenic mechanisms of bacterial fruit blotch.