Characterization of the Aspergillus nidulans Monodictyphenone Gene Cluster

Abstract

Deletion of cclA, a component of the COMPASS complex of Aspergillus nidulans, results in the production of monodictyphenone and emodin derivatives. Through a set of targeted deletions in a cclA deletion strain, we have identified the genes required for monodictyphenone and emodin analog biosynthesis. Identification of an intermediate, endocrocin, from an mdpH⌬ strain suggests that mdpH might encode a decarboxylase. Furthermore, by replacing the promoter of mdpA (a putative aflJ homolog) and mdpE (a putative aflR homolog) with the inducible alcA promoter, we have confirmed that MdpA functions as a coactivator. We propose a biosynthetic pathway for monodictyphenone and emodin derivatives based on bioinformatic analysis and characterization of biosynthetic intermediates.

Comparative genomic analysis of the thermophilic biomass-degrading fungi Myceliophthora thermophila and Thielavia terrestris

“…18 Compared to the paradigmatic cellulase producer, Trichoderma reesei, the two 19 thermophiles have similar complements of GH proteins. A major difference is the clear 20 expansion of the GH61 family, and to a lesser extent the GH10 and GH11 xylanases, in members 21 of the family Chaetomiaceae examined in this study (at least 18 GH61 proteins for the 22 Tables 5 and 6). The GH61 family was 23 originally classified on the basis of very weak endo-1,4-β-D-glucanase activity found in one 24 family member 9 .…”

“…In contrast, transcripts encoding enzymes that deconstruct plant 20 cell walls are upregulated only during growth on barley or alfalfa straws. For growth on barley 21 straw, the induced transcripts correspond closely with the substrate composition; genes for 22 cellulolytic and xylanolytic enzymes are highly upregulated, followed by genes for arabinanases, 23 mannanases and to a lesser extent pectinolytic enzymes. However, such simple matching of gene 24 activity and substrate constituents does not extend to growth on alfalfa straw, especially for T. 25 terrestris.…”

“…One way 19 to overcome these obstacles is to raise the reaction temperature, thereby increasing hydrolytic 20 rates and reducing contamination risks. However, implementing higher reaction temperatures 21 requires the deployment of enzymes that are more thermostable than the available preparations 22 from mesophilic fungi. Additional advantages of elevated hydrolysis temperatures include 23 enhanced mass transfer, reduced substrate viscosity, and the potential for enzyme recycling 1 .…”

“…[9][10][11][12][13][14][15][16][17][18][19][20][21] Mbp genome. These three species within the family Chaetomiaceae share 6,279 three-way 22 orthologs and extensive synteny with >6,000 genes in syntenic blocks between each pair, 23 including four blocks of >400 genes between M. thermophila and T. terrestris (Supplementary Table 1). The breakpoints of the synteny blocks often coincide with 25 AT-rich repetitive regions (Fig.…”

“…The biphasic temperature 19 profile of cell wall decomposition suggests that the proteins secreted by the thermophiles contain 20 multiple biomass enzymes, some of which have temperature optima at 60 °C, whereas others 21 have optima around 40 °C. 22 To determine whether biomass-degrading enzymes from these thermophiles possess 23 distinct temperature optima, we successfully cloned and expressed in Aspergillus niger the genes 24 encoding seven xylanases from the thermophiles and tested their biochemical properties. The 25 temperature optima for these xylanases range from 45 °C to 70 °C ( Table 2).…”