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Role of the LysR ‐type transcriptional regulator PecT and DNA supercoiling in the thermoregulation of pel genes, the major virulence factors in D ickeya dadantii
Author(s) -
Hérault Elodie,
Reverchon Sylvie,
Nasser William
Publication year - 2014
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12198
Subject(s) - biology , virulence , repressor , dna supercoil , dna , regulator , promoter , gene , microbiology and biotechnology , genetics , gene expression , dna replication
Summary Bacteria are colonizers of various environments and host organisms, and they are often subjected to drastic temperature variations. D ickeya dadantii is a pathogen infecting a wide range of plant species. Soft rot, the visible symptom, is mainly due to the production of pectate lyases ( P els) that destroy plant cell walls. The production of P els is controlled by a complex regulation system that responds to various stimuli, such as the presence of pectin, growth phase and temperature. Despite numerous regulatory studies, the thermoregulation mechanism of P el production remains unexplained. Here, we show that PecT , a previously identified repressor, modulates pel gene expression in a temperature‐dependent manner, and we demonstrate that PecT binding on pel promoters increases concomitantly with temperature. High temperatures relax the DNA in D . dadantii , and remarkably, artificial relaxation of DNA at low temperatures increases PecT binding to DNA . Deletion of pecT augmented the capacity of D . dadantii to initiate soft‐rot symptoms at high temperatures. These results reveal that DNA topology and PecT act in concert to fine‐tune D . dadantii virulence in response to temperature. This novel combination between DNA topology and a conventional transcriptional regulator extends our understanding of the thermoregulation mechanisms involved in bacterial virulence.