title: Discovery of plant phenolic compounds that act as type III secretion system inhibitors or inducers of the fire blight pathogen, Erwinia amylovora.
abstract: Erwinia amylovora causes a devastating disease called fire blight in rosaceous plants. The type III secretion system (T3SS) is one of the important virulence factors utilized by E. amylovora in order to successfully infect its hosts. By using a green fluorescent protein (GFP) reporter construct combined with a high-throughput flow cytometry assay, a library of phenolic compounds and their derivatives was studied for their ability to alter the expression of the T3SS. Based on the effectiveness of the compounds on the expression of the T3SS pilus, the T3SS inhibitors 4-methoxy-cinnamic acid (TMCA) and benzoic acid (BA) and one T3SS inducer, trans-2-(4-hydroxyphenyl)-ethenylsulfonate (EHPES), were chosen for further study. Both the T3SS inhibitors (TMCA and BA) and the T3SS inducer (EHPES) were found to alter the expression of T3SS through the HrpS-HrpL pathway. Additionally, TMCA altered T3SS expression through the rsmBEa-RsmAEa system. Finally, we found that TMCA and BA weakened the hypersensitive response (HR) in tobacco by suppressing the T3SS of E. amylovora. In our study, we identified phenolic compounds that specifically targeted the T3SS. The T3SS inhibitor may offer an alternative approach to antimicrobial therapy by targeting virulence factors of bacterial pathogens.
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA.
authors.forename: Devanshi
authors.initials: D
authors.lastname: Khokhani
authors.forename: Chengfang
authors.initials: C
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Quan
authors.initials: Q
authors.lastname: Zeng
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yamazaki
authors.forename: William
authors.initials: W
authors.lastname: Hutchins
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Zhou
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.forename: Ching-Hong
authors.initials: CH
authors.lastname: Yang
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000187:drug effects*; D044084:Erwinia amylovora / Q000187:drug effects* / Q000378:metabolism*; D005434:Flow Cytometry; D015870:Gene Expression / Q000187:drug effects*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D010936:Plant Extracts / Q000302:isolation & purification / Q000378:metabolism*; D010944:Plants / Q000737:chemistry*; D015533:Transcriptional Activation
chemical_list: D000900:Anti-Bacterial Agents; D058947:Bacterial Secretion Systems; D010936:Plant Extracts; D049452:Green Fluorescent Proteins