Supplementary Materials Supplemental material supp_11_8_1055__index. an effect on virulence-related morphogenesis. INTRODUCTION Pathogenic fungi in the phylum basidiomycota include many potentially devastating agents of plant disease, such as the rust and smut fungi, as well as a small number of species that attack animal hosts. The phytopathogens include the smut fungus that has emerged as a model for obligate biotrophic fungi. can be grown as a saprophyte in culture, but the fungus is dependent on infection of maize or teosinte to complete sexual development (6, 54). Infection is initiated on the plant surface by mating of haploid yeast-like cells to form a filamentous, infectious dikaryon. The invasive filaments proliferate in the plant and ultimately incite large tumors that fill with black teliospores (2). In addition to mating, the switch from yeast-like to filamentous growth is triggered by low pH, low nitrogen, phosphate, and fatty acids (5, 27, 28, 34, 49). Recently, we showed that the morphological switch in response to specific fatty acids is influenced by peroxisomal -oxidation, thus raising the possibility that this process is important for the pathogenicity of (28). -Oxidation of fatty acids is important for the utilization of storage lipids or exogenous fatty acids to generate acetyl coenzyme A (acetyl-CoA) for central carbon metabolism (18). Four enzymatic steps are involved Rabbit polyclonal to ALS2CR3 in -oxidation and are catalyzed by the following enzymes: acyl-CoA dehydrogenase, enoyl-CoA hydratase, hydroxyacyl-CoA dehydrogenase, and GDC-0973 manufacturer ketoacyl-CoA thiolase (18). Processing of a fatty acid molecule yields acetyl-CoA as well as an acyl-CoA molecule that is shortened by two carbon units and available for further cycles of -oxidation. Most organisms have multiple GDC-0973 manufacturer enzymes for each GDC-0973 manufacturer of the four steps to accommodate fatty acids of different chain length, oxidation state, or other modifications, such as side chains (39). In mammals, -oxidation occurs in both peroxisomes and mitochondria (21, 60, 62). The peroxisome is thought to be responsible for the oxidation of long-chain GDC-0973 manufacturer fatty acids, and the mitochondrion oxidizes short-chain fatty acids and also performs the final oxidation step (21, 60). In addition, one type of -oxidation in the mitochondria of mammals involves a trifunctional enzyme that catalyzes the final three reactions, and peroxisomal -oxidation in mammals and other organisms involves a multifunctional enzyme (Fox or Mfe) with the enoyl-CoA hydratase and 3-OH-acyl-CoA dehydrogenase activities (21, 52, 60). Fungal -oxidation is not well characterized, and it was previously thought that fungi might have only peroxisomal -oxidation because lacks the enzymes for the mitochondrial process (30, 57, 59). However, both mitochondrial -oxidation and peroxisomal -oxidation have been convincingly demonstrated in (23, 35, 36). In this fungus, disruption of the gene for the peroxisomal multifunctional enzyme FoxA does not influence growth on short-chain fatty acids but does attenuate growth on long-chain fatty acids (35). In contrast, disruption of the gene encoding the predicted mitochondrial -oxidation enzyme enoyl-CoA hydratase eliminates growth on short-chain fatty acids and the amino acids isoleucine and valine and attenuates growth on long-chain fatty acids. Interestingly, loss of EchA also sensitizes to oleic acid and hexanoic acid due to the accumulation of toxic intermediates, and a similar phenotype is observed upon loss of the gene, encoding the mitochondrial hydroxyacyl-CoA dehydrogenase (23, 35, 36). Disruption of the gene for the short-chain acyl-CoA dehydrogenase that catalyzes the first step in mitochondrial -oxidation also eliminates growth on short-chain but not long-chain fatty acids. A double mutant with disruptions in both and did not show sensitivity to oleic acid, in further support for the hypothesis regarding accumulation of toxic intermediates (36). Similar results were obtained with a double mutant in (4). Recent surveys of the pathways encoded in more than 50 fungal genomes revealed that most fungi possess both mitochondrial and peroxisomal pathways (8, 52). For on cotyledons and defects in -oxidation and peroxisome biogenesis block appressorium-based invasion in species, and (1, 3, 12, 14, 25, 26, 46, 64). Therefore, -oxidation represents an attractive target for the development of control strategies..