Changes in Aspergillus nidulans gene expression induced by bafilomycin, a Streptomyces-produced antibiotic

Abstract

In natural environments bacteria and filamentous fungi often compete for the same resources. Consequently, production of antibiotic secondary metabolites and defence mechanisms against these compounds have evolved in these organisms. An experimental model has been developed to study the response in fungi exposed to one such antibiotic. The filamentous fungus Aspergillus nidulans was treated with bafilomycin B, , a Streptomyces-produced antibiotic which reduces radial growth rate and induces morphological changes in fungi. mRNA differential display was used to study changes in fungal gene expression. For five genes, changes in abundance of the corresponding mRNAs, directly or indirectly caused by bafilomycin, were observed. Of these, three were upregulated and two repressed. With four of these the change in mRNA abundance measured ranged from 10-t o 60-fold. However, for one gene the mRNA was only detected after bafilomycin treatment. One of the downregulated mRNAs encodes ASPNDI, a glycoprotein that belongs to a known family of antigens identified in aspergilloma patients. One up-regulated mRNA shows sequence similarities, a t the amino acid level, with a cell-wall protein of Saccharomyces cerevisiae. The remaining three genes were also cloned and sequenced; their sequences do not correspond to known genes in A. nidulans, and no similarities with published nucleotide or protein sequences in other organisms were found. These results indicate the feasibility of using mRNA differential display to study interactions between bacteria and filamentous fungi.

Proteome analysis of Aspergillus nidulans reveals proteins associated with the response to the antibiotic concanamycin A, produced by Streptomyces species

“…The bafilomycins, and the closely related concanamycins, are inhibitors of vacuolar ATPases, produced by various Streptomyces species (Bowman et al 1988;Dro¨se and Altendorf 1996). Previously, we used the mRNA differential display technique (RNA-DD; Liang and Pardee 1992) to screen for genes in Aspergillus nidulans that exhibited changes in expression upon treatment with bafilomycin B1 (Melin et al 1999). We found that the antibiotic up-regulated the expression of three genes, whereas the expression of two genes was down-regulated.…”

“…The difference in gene expression varied from 10-fold to one extreme case in which expression of the gene in question was only detectable in the bafilomycin-treated fungus. At that time, the biological functions of most of these five genes were unknown (Melin et al 1999). However, one of the down-regulated genes was later found to encode a cell wall-associated zinc-binding protein, Aspnd1 (Segurado et al 1999).…”

Indole-Diterpene Gene Cluster fromAspergillus flavus

“…AF104 does not appear to have an ortholog in the pax gene cluster. Although AF106 has a very small open reading frame (encoding 87 amino acids), the predicted polypeptide shares significant similarity with the C terminus of A. nidulans AN6743 and with A. nidulans BinA, with the latter being defined as functional by the isolation of an expressed sequence tag (27 3-kb BamHI fragment of pSZ-21 containing ggsA was subcloned into pBluescript II KS(ϩ) to generate pSZ-22, which was used as a template to extend the sequence data previously derived from the 218-bp insert in pSZ-2. This sequence (ggsA) contained the five conserved domains found in other prenyl diphosphate synthase genes (8) and had significant identity to paxG (E value of 5eϪ40).…”

Bacterial-Fungal Interactions: Hyphens between Agricultural, Clinical, Environmental, and Food Microbiologists

“…Indeed, various studies have used "omics" techniques to probe the changes that occur during BFIs at the subcellular level (25,94,167,231,235,259,281,352); for example, a recent study of the arbuscular mycorrhizal fungus Gigaspora margarita using combined proteomic and lipid metabolite profiling revealed that the presence of endobacteria had a significant impact on fungal physiology (331). Targeted approaches assessing the proteomic or transcriptomic responses of one BFI partner to molecules produced by the other also allow the testing of specific hypotheses relating to BFIs, such as responses to antibiotics (245,246). However, many mechanistic investigations of BFIs are performed in controlled microcosms with a very limited number of interacting microorganisms, whereas natural interactions often involve a complex community of microorganisms whose combined properties may be unpredictable.…”