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Molecular responses in Aspergillus nidulans to Streptomyces-produced inhibitors of V-ATPases

Melin, Petter (2002). Molecular responses in Aspergillus nidulans to Streptomyces-produced inhibitors of V-ATPases. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae. Agraria, 1401-6249 ; 361
ISBN 91-576-6183-9
[Doctoral thesis]

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Abstract

In nature filamentous fungi and bacteria compete for space and nutrients. Both kinds of organisms have evolved mechanisms such as synthesis of antibiotic secondary metabolites to defeat other microbes. Studies of synthesis of antibiotics and microbial ecology in general have important applications in both agriculture and medicine. This thesis deals with molecular responses in the filamentous fungus Aspergillus nidulans to inhibitors of V-ATPases, bafilomycin and concanamycin. These antibiotics are produced by various species within the bacterial genus Streptomyces. The main function of V-ATPases in fungi is to keep the vacuoles acidified. Inhibition of V-ATPases leads to fungal hyperbranching and extremely reduced radial growth. Changes at the molecular level were observed when the fungus was treated with the antibiotics. Using mRNA differential display, five genes with changed expression after treatment were identified. A proteomic approach was used to screen for affected proteins, and 20 proteins displayed changed abundance after antibiotic treatment. Five of these were successfully identified. Most of these gene products were previously unknown, but one could be directly linked to disrupted V-ATPases. The function of several others could not, at this point, be directly related to inhibited V-ATPases. In this thesis, two genes were further characterised. The first of them, vmaA, encodes a major subunit of the V-ATPase. Disruption of vmaA confirmed that the V-ATPase is the main target for bafilomycin and concanamycin in A. nidulans. This mutant strain promises to be a useful tool in further studies of the identified gene products. The most extensively studied gene in this work is phiA. This gene was identified by mRNA differential display, and was up-regulated by bafilomycin. Surprisingly, phiA was found to be essential for normal asexual development. This is intriguing, and several hypotheses can be formulated, of which the most likely is that the induced phiA expression after inhibited V-ATPases is due to secondary effects in the fungus, i.e. caused by triggering growth arrest. In this thesis, several molecular methods, e.g. differential display, proteomics, and immunohisto-chemistry, have been used successfully to study interactions between bacteria and filamentous fungi.

Authors/Creators:Melin, Petter
Title:Molecular responses in Aspergillus nidulans to Streptomyces-produced inhibitors of V-ATPases
Year of publishing :April 2002
Volume:361
Number of Pages:38
Papers/manuscripts:
NumberReferences
ALLI. Melin, P., Schnürer, J. and Wagner, E.G.H. 1999. Changes in Aspergillus nidulans gene expression induced by bafilomycin, a Streptomyces -produced antibiotic. Microbiology 145:1115-1122. II. Melin, P., Schnürer, J., and Wagner, E.G.H. 2002. Proteome analysis of Aspergillus nidulans reveals proteins associated with the response to the antibiotic concanamycin A, produced by Streptomyces species. Molecular genetics and genomics 267:695-702. III. Melin, P., Schnürer, J., and Wagner, E.G.H. 2002. Disruption of the gene for the V-ATPase subunit A results in inhibition of normal growth and abolished sporulation in Aspergillus nidulans. Manuscript. IV. Melin, P., Schnürer, J., and Wagner, E.G.H. 2002. Characterization of phiA, a gene essential for phialide development in Aspergillus nidulans. Manuscript.
Place of Publication:Uppsala
ISBN for printed version:91-576-6183-9
ISSN:1401-6249
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:X Agricola extesions > X30 Life sciences
Subjects:Not in use, please see Agris categories
Agrovoc terms:aspergillus, molecular genetics, microbial ecology, mycology
Keywords:Emericella nidulans, bafilomycin, concanamycin, mRNA differential display, proteomics, targeted gene disruption, immunohistochemistry.
ID Code:238
Department:(NL, NJ) > Dept. of Microbiology (until 161231)
Deposited By: Petter Melin
Deposited On:14 Apr 2003 00:00
Metadata Last Modified:02 Dec 2014 10:02

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