Location: Emerging Pests and Pathogens ResearchTitle: The ECF sigma factor, PSPTO_1043, in Pseudomonas syringae pv. tomato DC3000 is induced by oxidative stress and regulates genes involved in oxidative stress response Author
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2017
Publication Date: 7/12/2017
Publication URL: http://handle.nal.usda.gov/10113/5763100
Citation: Butcher, B., Bao, Z., Wilson, J., Stodghill, P., Swingle, B.M., Filiatrault, M.J., Schneider, D.J., Cartinhour, S.W. 2017. The ECF sigma factor, PSPTO_1043, in Pseudomonas syringae pv. tomato DC3000 is induced by oxidative stress and regulates genes involved in oxidative stress response. PLoS One. DOI: 10.1371/journal.pone.0180340. Interpretive Summary: Pseudomonas syringae, a bacterial plant pathogen, possesses extracytoplasmic function (ECF) sigma factors, which respond rapidly to changes in the plant environment and regulate the response of genes necessary for the bacteria's survival. PSPTO_1043 is one of P.syringae's ten ECF sigma factors. It is not known what external signal activates PSPTO_1043 nor the genes whose expression it controls. The objective of this work was to fill in these knowledge gaps. Singlet oxygen (02), a chemical produced by plant defense system, was found to activate PSPTO_1043. When PSPTO_1043 was expressed, expression of 12 other genes was found to be significantly increased. This information significantly expands the current knowledge of how P.syringae recognizes and responds to changes in its environment. This increased understanding of how bacteria, like P.syringae, survive within plants and cause disease will enable other scientists to develop better pest-resistant crop varieties and control strategies.
Technical Abstract: The bacterial plant pathogen Pseudomonas syringae adapts to changes in the environment by modifying its gene expression profile. In many cases, the response is mediated by the activation of extracytoplasmic function (ECF) sigma factors that direct RNA polymerase to transcribe specific sets of genes. In this study we focus on PSPTO_1043, one of ten ECF sigma factors in P. syringae pv. Tomato DC3000 (DC3000). PSPTO_1043, together with PSPTO_1042, encode an RpoE~Rsp~/ChrR-like sigma/anti-sigma factor pair. Although this gene pair is unique to the P. syringae group among the pseudomonads, homologous genes can be found in photosynthetic genera such as Rhodospirillum, Thalassospira, Phaeospirillum and Parvibaculum. Using ChIP-Seq, we detected 137 putative PSPTO_1043 binding sites and identified a likely promoter motif. We characterized 13 promoter candidates, six of which regulate genes that appear to be found only in P. syringae. PSPTO_1043 responds to the presence of singlet oxygen (^1^O~2~) and tert-butyl hydroperoxide (tBOOH) and several of the genes regulated by PSPTO_1043 appear to be involved in response to oxidative stress.