title: An extracytoplasmic function sigma factor-mediated cell surface signaling system in Pseudomonas syringae pv. tomato DC3000 regulates gene expression in response to heterologous siderophores.
abstract: The diversity of regulatory systems encoded by bacteria provides an indication of the variety of stresses and interactions that these organisms encounter in nature. We have been investigating how the plant pathogen Pseudomonas syringae pv. tomato DC3000 responds to iron limitation and have focused on the iron starvation (IS) sigma factors to identify regulon members and to explore the mechanistic details of genetic control for this class of regulators. In the study described in this report, we used chromatin immunoprecipitation paired with high-throughput sequencing (ChIP-Seq) to screen the genome for locations associated with binding of the P. syringae IS sigma factor PSPTO_1203. We used multiple methods to demonstrate differential regulation of two genes identified in the ChIP-Seq screen and characterize the promoter elements that facilitate PSPTO_1203-dependent regulation. The genes regulated by PSPTO_1203 encode a TonB-dependent transducer (PSPTO_1206) and a cytoplasmic membrane protein (PSPTO_2145), which is located in the P. syringae pyoverdine cluster. Additionally, we identified siderophores that induce the activity of PSPTO_1203 and used this information to investigate the functional components of the signal transduction cascade.
authors.affiliation: United States Department of Agriculture-Agricultural Research Service, Ithaca, New York 14853, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Markel
authors.forename: Charlene
authors.initials: C
authors.lastname: Maciak
authors.forename: Bronwyn G
authors.initials: BG
authors.lastname: Butcher
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Myers
authors.forename: Paul
authors.initials: P
authors.lastname: Stodghill
authors.forename: Zhongmeng
authors.initials: Z
authors.lastname: Bao
authors.forename: Sam
authors.initials: S
authors.lastname: Cartinhour
authors.forename: Bryan
authors.initials: B
authors.lastname: Swingle
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism; D018551:Solanum lycopersicum / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D011485:Protein Binding; D044224:Pseudomonas syringae / Q000235:genetics / Q000378:metabolism*; D017262:Siderophores / Q000378:metabolism*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D017262:Siderophores; D012808:Sigma Factor; D007501:Iron