We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The phytopathogen Xanthomonas campestris utilizes the divergently transcribed pobA/pobR locus for 4‐hydroxybenzoic acid recognition and degradation to promote virulence.
- Authors
Chen, Bo; Li, Rui‐Fang; Zhou, Lian; Qiu, Jia‐Hui; Song, Kai; Tang, Ji‐Liang; He, Ya‐Wen
- Abstract
Xanthomonas campestris pv. campestris (Xcc) is the causal agent of black rot in crucifers. Our previous findings revealed that Xcc can degrade 4‐hydroxybenzoic acid (4‐HBA) via the β‐ketoadipate pathway. This present study expands on this knowledge in several ways. First, we show that infective Xcc cells induce in situ biosynthesis of 4‐HBA in host plants, and Xcc can efficiently degrade 4‐HBA via the pobA/pobR locus, which encodes a 4‐hydroxybenzoate hydroxylase and an AraC‐family transcription factor respectively. Next, the transcription of pobA is specifically induced by 4‐HBA and is positively regulated by PobR, which is constitutively expressed in Xcc. 4‐HBA directly binds to PobR dimers, resulting in activation of pobA expression. Point mutation and subsequent isothermal titration calorimetry and size exclusion chromatography analysis identified nine key conserved residues required for 4‐HBA binding and/or dimerization of PobR. Furthermore, overlapping promoters harboring fully overlapping −35 elements were identified between the divergently transcribed pobA and pobR. The 4‐HBA/PobR dimer complex specifically binds to a 25‐bp site, which encompasses the −35 elements shared by the overlapping promoters. Finally, GUS histochemical staining and subsequent quantitative assay showed that both pobA and pobR genes are transcribed during Xcc infection of Chinese radish, and the strain ΔpobR exhibited compromised virulence in Chinese radish. These findings suggest that the ability of Xcc to survive the 4‐HBA stress might be important for its successful colonization of host plants.
- Subjects
XANTHOMONAS campestris; ISOTHERMAL titration calorimetry; GEL permeation chromatography; HOST plants; PLANT colonization; TRANSCRIPTION factors
- Publication
Molecular Microbiology, 2020, Vol 114, Issue 5, p870
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/mmi.14585