RpoN1 (sigma factor 54) contributes to the virulence of Paracidovorax citrulli by regulating the expression of type IV pili PilA
Abstract 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...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMC
2025-03-01
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| Series: | Phytopathology Research |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s42483-025-00311-x |
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| Summary: | Abstract 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. |
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| ISSN: | 2524-4167 |