indole-3-acetonitrile and indole

The plant hormone indole-3-acetic acid (IAA) is one of the main signals playing a role in the communication between host and endophytes. Endophytes can synthesize IAA de novo to influence the IAA homeostasis in plants. Although much is known about IAA biosynthesis in microorganisms, there is still less known about the pathway by which IAA is synthesized in fungal endophytes. The aim of this study is to examine a possible IAA biosynthesis pathway in

Topics: Arabidopsis; Arabidopsis Proteins; Ascomycota; Benzimidazoles; Culture Media, Conditioned; Endophytes; Genome, Fungal; Glycolates; Host Adaptation; Host Specificity; Indoleacetic Acids; Indoles; Metabolic Networks and Pathways; Phthalimides; Plant Roots; Triazoles; Tryptophan

The mycotoxin fumonisin B1 (FB1) causes the accumulation of reactive oxygen species (ROS) which then leads to programmed cell death (PCD) in Arabidopsis. In the process of studying FB1-induced biosynthesis of glucosinolates, we found that indole glucosinolate (IGS) is involved in attenuating FB1-induced PCD. Treatment with FB1 elevates the expression of genes related to the biosynthesis of camalexin and IGS. Mutants deficient in aliphatic glucosinolate (AGS) or camalexin biosynthesis display similar lesions to Col-0 upon FB1 infiltration; however, the cyp79B2 cyp79B3 double mutant, which lacks induction of both IGS and camalexin, displays more severe lesions. Based on the fact that the classic myrosinase β-thioglucoside glucohydrolase (TGG)-deficient double mutant tgg1 tgg2, rather than atypical myrosinase-deficient mutant pen2-2, is more sensitive to FB1 than Col-0, and the elevated expression of TGG1, but not of PEN2, correlates with the decrease in IGS, we conclude that TGG-dependent IGS hydrolysis is involved in FB1-induced PCD. Indole-3-acetonitrile (IAN) and indole-3-carbinol (I3C), the common derivatives of IGS, were used in feeding experiments, and this rescued the severe cell death phenotype, which is associated with reduced accumulation of ROS as well as increased activity of antioxidant enzymes and ROS-scavenging ability. Despite the involvement of indole-3-acetic acid (IAA) in restricting FB1-induced PCD, feeding of IAN and I3C attenuated FB1-induced PCD in the IAA receptor mutant tir1-1 just as in Col-0. Taken together, our results indicate that TGG-catalyzed breakdown products of IGS decrease the accumulation of ROS by their antioxidant behavior, and attenuate FB1 induced PCD in an IAA-independent way.

Topics: Arabidopsis; Arabidopsis Proteins; Cell Death; Cytochrome P-450 Enzyme System; Fumonisins; Glucosinolates; Glycoside Hydrolases; Indoleacetic Acids; Indoles; Mutation; Thiazoles

Indole is a signalling molecule, produced by a number of Gram-positive and Gram-negative bacteria both in nature as well as clinical environments. Here, we explored the effect of bacterial indole and one of its main derivatives on the virulence of the fungal pathogen Candida albicans.. We found that indole and its derivate indole-3-acetonitrile (IAN) did not affect the viability of C. albicans. Interestingly, indole and IAN repressed C. albicans biofilm formation as well as the attachment of C. albicans to intestinal epithelial HT-29 cells and inhibited the ability of the yeast to make filaments that are the main virulence factor of C. albicans. In addition, we used the heterologous model host Caenorhabditis elegans to demonstrate in vivo that the presence of indole or IAN attenuates C. albicans infection (P = 0.0188 and P < 0.0001 for indole and IAN, respectively, compared to worms exposed to C. albicans DAY185 alone) and decreases fungal colonization in the nematode gut. Importantly, quantitative real-time polymerase chain reaction (qRT-PCR) results showed that in C. albicans, indole and IAN strongly stimulated the transcription of NRG1.. Indole and IAN attenuates fungal virulence by regulating the transcription of NRG1, a transcriptional factor that influences filamentation and biofilm formation in C. albicans.. Our findings indicate that the bacterial signalling molecules indole and its derivatives play an inter-kingdom role in dynamic network of microbiota and directly modulate the virulence of fungal C. albicans via NRG1.

Topics: Animals; Biofilms; Caenorhabditis elegans; Candida albicans; HT29 Cells; Humans; Indoles; Transcription Factors; Virulence; Virulence Factors

Intercellular signal indole and its derivative hydroxyindoles inhibit Escherichia coli biofilm and diminish Pseudomonas aeruginosa virulence. However, indole and bacterial indole derivatives are unstable in the microbial community because they are quickly degraded by diverse bacterial oxygenases. Hence, this work sought to identify novel, non-toxic, stable and potent indole derivatives from plant sources for inhibiting the biofilm formation of E. coli O157:H7 and P. aeruginosa. Here, plant auxin 3-indolylacetonitrile (IAN) was found to inhibit the biofilm formation of both E. coli O157:H7 and P. aeruginosa without affecting its growth. IAN more effectively inhibited biofilms than indole for the two pathogenic bacteria. Additionally, IAN decreased the production of virulence factors including 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), pyocyanin and pyoverdine in P. aeruginosa. DNA microarray analysis indicated that IAN repressed genes involved in curli formation and glycerol metabolism, whereas IAN induced indole-related genes and prophage genes in E. coli O157:H7. It appeared that IAN inhibited the biofilm formation of E. coli by reducing curli formation and inducing indole production. Also, corroborating phenotypic results of P. aeruginosa, whole-transcriptomic data showed that IAN repressed virulence-related genes and motility-related genes, while IAN induced several small molecule transport genes. Furthermore, unlike bacterial indole derivatives, plant-originated IAN was stable in the presence of either E. coli or P. aeruginosa. Additionally, indole-3-carboxyaldehyde was another natural biofilm inhibitor for both E. coli and P. aeruginosa.

Topics: Acetonitriles; Adhesins, Escherichia coli; Bacterial Proteins; Biofilms; Escherichia coli O157; Indoles; Microscopy, Electron, Scanning; Oligonucleotide Array Sequence Analysis; Pseudomonas aeruginosa; RNA, Bacterial; Virulence; Virulence Factors

Bacteria use diverse signaling molecules to ensure the survival of the species in environmental niches. A variety of both gram-positive and gram-negative bacteria produce large quantities of indole that functions as an intercellular signal controlling diverse aspects of bacterial physiology.. In this study, we sought a novel role of indole in a gram-positive bacteria Paenibacillus alvei that can produce extracellular indole at a concentration of up to 300 μM in the stationary phase in Luria-Bertani medium. Unlike previous studies, our data show that the production of indole in P. alvei is strictly controlled by catabolite repression since the addition of glucose and glycerol completely turns off the indole production. The addition of exogenous indole markedly inhibits the heat resistance of P. alvei without affecting cell growth. Observation of cell morphology with electron microscopy shows that indole inhibits the development of spore coats and cortex in P. alvei. As a result of the immature spore formation of P. alvei, indole also decreases P. alvei survival when exposed to antibiotics, low pH, and ethanol. Additionally, indole derivatives also influence the heat resistance; for example, a plant auxin, 3-indolylacetonitrile dramatically (2900-fold) decreased the heat resistance of P. alvei, while another auxin 3-indoleacetic acid had a less significant influence on the heat resistance of P. alvei.. Together, our results demonstrate that indole and plant auxin 3-indolylacetonitrile inhibit spore maturation of P. alvei and that 3-indolylacetonitrile presents an opportunity for the control of heat and antimicrobial resistant spores of gram-positive bacteria.

Topics: Acetonitriles; Cell Wall; Growth Inhibitors; Indoles; Microscopy, Electron, Transmission; Paenibacillus; Signal Transduction; Spores, Bacterial

In this study we investigated the role of indole-3-acetonitrile, indole-3-carbinol, indole and tryptophan in the formation of N-nitroso compounds in green cabbage extracts. Green cabbage extracts were separated by gel permeation chromatography. Fractions were treated with nitrite, tested for mutagenicity and analysed for total N-nitroso content. Fractions in which spiked indole-3-acetonitrile, indole-3-carbinol, indole and tryptophan eluted appeared to be low in mutagenic activity and contained relatively small amounts of N-nitroso compounds. To detect indole compounds other than the ones used in the gel permeation chromatography experiments, high-performance liquid chromatography and gas chromatography-mass spectrometry analyses were performed of green cabbage extracts. Indole-3-carboxaldehyde was found to be the most commonly occurring indole compound, but it did not show direct mutagenic activity upon nitrite treatment. Indole-3-acetonitrile was the second most common compound; although it was mutagenic after nitrite treatment, its contribution to the mutagenicity of nitrite-treated green cabbage was roughly estimated to be only 2%. No other indole compounds were detected. From this study we conclude that neither the tested indole compounds nor indole-3-carboxaldehyde play a significant role in the formation of direct mutagenic N-nitroso compounds in nitrite-treated green cabbage extracts.

Topics: Brassica; Chromatography, Gel; Chromatography, High Pressure Liquid; Gas Chromatography-Mass Spectrometry; Glucosinolates; Indoles; Mutagens; Nitroso Compounds; Salmonella typhimurium; Tryptophan