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Fungus Aspergillus Nidulans (fungus + aspergillus_nidulan)
Kinds of Fungus Aspergillus Nidulans Selected AbstractsImpact of fungal drug transporters on fungicide sensitivity, multidrug resistance and virulence,PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2006Maarten A de Waard Abstract Drug transporters are membrane proteins that provide protection for organisms against natural toxic products and fungicides. In plant pathogens, drug transporters function in baseline sensitivity to fungicides, multidrug resistance (MDR) and virulence on host plants. This paper describes drug transporters of the filamentous fungi Aspergillus nidulans (Eidam) Winter, Botrytis cinerea Pers and Mycosphaerella graminicola (Fückel) Schroter that function in fungicide sensitivity and resistance. The fungi possess ATP-binding cassette (ABC) drug transporters that mediate MDR to fungicides in laboratory mutants. Similar mutants are not pronounced in field resistance to most classes of fungicide but may play a role in resistance to azoles. MDR may also explain historical cases of resistance to aromatic hydrocarbon fungicides and dodine. In clinical situations, MDR development in Candida albicans (Robin) Berkhout mediated by ABC transporters in patients suffering from candidiasis is common after prolonged treatment with azoles. Factors that can explain this striking difference between agricultural and clinical situations are discussed. Attention is also paid to the risk of MDR development in plant pathogens in the future. Finally, the paper describes the impact of fungal drug transporters on drug discovery. Copyright © 2006 Society of Chemical Industry [source] 2-Methylisocitrate lyases from the bacterium Escherichia coli and the filamentous fungus Aspergillus nidulansFEBS JOURNAL, Issue 12 2001Characterization, comparison of both enzymes In Escherichia coli and Aspergillus nidulans, propionate is oxidized to pyruvate via the methylcitrate cycle. The last step of this cycle, the cleavage of 2-methylisocitrate to succinate and pyruvate is catalysed by 2-methylisocitrate lyase. The enzymes from both organisms were assayed with chemically synthesized threo -2-methylisocitrate; the erythro -diastereomer was not active. 2-Methylisocitrate lyase from E. coli corresponds to the PrpB protein of the prp operon involved in propionate oxidation. The purified enzyme has a molecular mass of approximately 32 kDa per subunit, which is lower than those of isocitrate lyases from bacterial sources (, 48 kDa). 2-Methylisocitrate lyase from A. nidulans shows an apparent molecular mass of 66 kDa per subunit, almost equal to that of isocitrate lyase of the same organism. Both 2-methylisocitrate lyases have a native homotetrameric structure as identified by size-exclusion chromatography. The enzymes show no measurable activity with isocitrate. Starting from 250 mm pyruvate, 150 mm succinate and 10 µm PrpB, the enzymatically active stereoisomer could be synthesized in 1% yield. As revealed by chiral HPLC, the product consisted of a single enantiomer. This isomer is cleaved by 2-methylisocitrate lyases from A. nidulans and E. coli. The PrpB protein reacted with stoichiometric amounts of 3-bromopyruvate whereby the activity was lost and one amino-acid residue per subunit became modified, most likely a cysteine as shown for isocitrate lyase of E. coli. PrpB exhibits 34% sequence identity with carboxyphosphoenolpyruvate phosphonomutase from Streptomyces hygroscopicus, in which the essential cysteine residue is conserved. [source] Reducing the cost of resistance; experimental evolution in the filamentous fungus Aspergillus nidulansJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2006S. E. SCHOUSTRA Abstract We have studied compensatory evolution in a fludioxonil resistant mutant of the filamentous fungus Aspergillus nidulans. In an evolution experiment lasting for 27 weeks (about 3000 cell cycles) 35 parallel strains of this mutant evolved in three different environmental conditions. Our results show a severe cost of resistance (56%) in the absence of fludioxonil and in all conditions the mutant strain was able to restore fitness without loss of the resistance. In several cases, the evolved strain reached a higher fitness than the original sensitive ancestor. Fitness compensation occurred in one, two or three discrete steps. Genetic analysis of crosses between different evolved strains and between evolved and ancestral strains revealed interaction between compensatory mutations and provided information on the number of loci involved in fitness compensation. In addition, we discuss the opportunities for the experimental study of evolutionary processes provided by the filamentous fungus A. nidulans. [source] Developmental regulation of the glyoxylate cycle in the human pathogen Penicillium marneffeiMOLECULAR MICROBIOLOGY, Issue 6 2006David Cánovas Summary Penicillium marneffei is a thermally dimorphic opportunistic human pathogen with a saprophytic filamentous hyphal form at 25°C and a pathogenic unicellular yeast form at 37°C. During infection. P. marneffei yeast cells exist intracellularly in macrophages. To cope with nutrient deprivation during the infection process, a number of pathogens employ the glyoxylate cycle to utilize fatty acids as carbon sources. The genes which constitute this pathway have been implicated in pathogenesis. To investigate acetate and fatty acid utilization, the acuD gene encoding a key glyoxylate cycle enzyme (isocitrate lyase) was cloned. The acuD gene is regulated by both carbon source and temperature in P. marneffei, being strongly induced at 37°C even in the presence of a repressing carbon source such as glucose. When introduced into the non-pathogenic monomorphic fungus Aspergillus nidulans, the P. marneffei acuD promoter only responds to carbon source. Similarly, when the A. nidulans acuD promoter is introduced into P. marneffei it only responds to carbon source suggesting that P. marneffei possesses both cis elements and trans -acting factors to control acuD by temperature. The Zn(II)2Cys6 DNA binding motif transcriptional activator FacB was cloned and is responsible for carbon source-, but not temperature-, dependent induction of acuD. The expression of acuD at 37°C is induced by AbaA, a key regulator of morphogenesis in P. marneffei, but deletion of abaA does not completely eliminate temperature-dependent induction, suggesting that acuD and the glyoxylate cycle are regulated by a complex network of factors in P. marneffei which may contribute to its pathogenicity. [source] Requirement of spermidine for developmental transitions in Aspergillus nidulansMOLECULAR MICROBIOLOGY, Issue 3 2002Yuan Jin Summary Deletion of the spermidine synthase gene in the fungus Aspergillus nidulans results in a strain, ,spdA, which requires spermidine for growth and accumulates putrescine as the sole polyamine. Vegetative growth but not sporulation or sterigmatocystin production is observed when ,spdA is grown on media supplemented with 0.05,0.10 mM exogenous spermidine. Supplementation of ,spdA with , 0.10 mM spermidine restores sterigmatocystin production and , 0.50 mM spermidine produces a phenotype with denser asexual spore production and decreased radial hyphal growth compared with the wild type. ,spdA spores germinate in unsupplemented media but germ tube growth ceases after 8 h upon which time the spores swell to approximately three times their normal diameter. Hyphal growth is resumed upon addition of 1.0 mM spermidine. Suppression of a G protein signalling pathway could not force asexual sporulation and sterigmatocystin production in ,spdA strains grown in media lacking spermidine but could force both processes in ,spdA strains supplemented with 0.05 mM spermidine. These results show that increasing levels of spermidine are required for the transitions from (i) germ tube to hyphal growth and (ii) hyphal growth to tissue differentiation and secondary metabolism. Suppression of G protein signalling can over-ride the spermidine requirement for the latter but not the former transition. [source] | |||||||||||||