title: Structure-activity relationships delineate how the maize pathogen Cochliobolus heterostrophus uses aromatic compounds as signals and metabolites.
abstract: The necrotrophic maize pathogen Cochliobolus heterostrophus senses plant-derived phenolic compounds, which promote nuclear retention of the redox-sensitive transcription factor ChAP1 and alter gene expression. The intradiol dioxygenase gene CCHD1 is strongly upregulated by coumaric and caffeic acids. Plant phenolics are potential nutrients but some of them are damaging compounds that need to be detoxified. Using coumaric acid as an inducer (16 to 160 μM), we demonstrated the rapid and simultaneous upregulation of most of the β-ketoadipate pathway genes in C. heterostrophus. A cchd1 deletion mutant provided genetic evidence that protocatechuic acid is an intermediate in catabolism of a wide range of aromatic acids. Aromatics catabolism was slowed for compounds showing toxicity, and this was strongly correlated with nuclear retention of GFP-ChAP1. The activity of a structure series of compounds showed complementary requirements for upregulation of CCHD1 and for ChAP1 nuclear retention. Thus, there is an inverse correlation between the ability to metabolize a compound and the stress response (ChAP1 nuclear retention) that it causes. The ability to metabolize phenolics and to respond to them as signals should be an advantage to plant pathogens and may explain the presence of at least two response pathways detecting these compounds.
authors.affiliation: Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Samer
authors.initials: S
authors.lastname: Shalaby
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Horwitz
authors.forename: Olga
authors.initials: O
authors.lastname: Larkov
mesh_terms: D000272:Adipates / Q000378:metabolism*; D001203:Ascomycota / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D002109:Caffeic Acids / Q000378:metabolism / Q000494:pharmacology; D003373:Coumaric Acids / Q000378:metabolism / Q000494:pharmacology; D004798:Enzymes / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D049452:Green Fluorescent Proteins; D054884:Host-Pathogen Interactions; D010084:Oxidation-Reduction; D010636:Phenols / Q000378:metabolism / Q000494:pharmacology*; D010935:Plant Diseases / Q000382:microbiology; D011801:Quinic Acid / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D003313:Zea mays / Q000737:chemistry / Q000382:microbiology*
chemical_list: D000272:Adipates; D002109:Caffeic Acids; D003373:Coumaric Acids; D004798:Enzymes; D005656:Fungal Proteins; D010636:Phenols; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D011801:Quinic Acid; C027316:3-oxoadipic acid; D049452:Green Fluorescent Proteins