Proteins interacting with CreA and CreB in the carbon catabolite repression network in Aspergillus nidulans

Abstract

In Aspergillus nidulans, carbon catabolite repression (CCR) is mediated by the global repressor protein CreA. The deubiquitinating enzyme CreB is a component of the CCR network. Genetic interaction was confirmed using a strain containing complete loss-of-function alleles of both creA and creB. No direct physical interaction was identified between tagged versions of CreA and CreB. To identify any possible protein(s) that may form a bridge between CreA and CreB, we purified both proteins from mycelia grown in media that result in repression or derepression. The purified proteins were analysed by LC/MS and identified using MaxQuant and Mascot databases. For both CreA and CreB, 47 proteins were identified in repressing and derepressing conditions. Orthologues of the co-purified proteins were identified in S. cerevisiae and humans. Gene ontology analyses of A. nidulans proteins and yeast and human orthologues were performed. Functional annotation analysis revealed that proteins that preferentially interact with CreA in repressing conditions include histones and histone transcription regulator 3 (Hir3). Proteins interacting with CreB tend to be involved in cellular transportation and organization. Similar findings were obtained using yeast and human orthologues, although the yeast background generated a number of other biological processes involving Mig1p which were not present in the A. nidulans or human background analyses. Hir3 was present in repressing conditions for CreA and in both growth conditions for CreB, suggesting that Hir3, or proteins interacting with Hir3, could be a possible target of CreB.

Regulation of Aspergillus nidulans CreA-Mediated Catabolite Repression by the F-Box Proteins Fbx23 and Fbx47

“…This is in agreement with a previous study where increased ubiquitylation of CreA (or of a protein immunoprecipitating together with CreA) was observed in the presence of xylan compared to glucose-rich conditions ( 27 ). The deubiquitylation complex CreB/CreC is thought to remove ubiquitin molecules from CreA, thereby leading to the presence of an active CreA protein ( 38 ), although no direct interaction of CreA with CreB/CreC was found in this work or in a previous study ( 72 , 73 ). It therefore remains to be determined with which factor of the repressor complex (de)ubiquitylation takes place.…”

The Aspergillus flavus Phosphatase CDC14 Regulates Development, Aflatoxin Biosynthesis and Pathogenicity

“…As amylase was considered to be associated with pathogenicity in Aspergillus spp . (Alam and Kelly, 2017 ), we detected the activity of amylase in the different strains, and the results showed that the activity of amylase was significantly decreased in Δ CDC14 compared to WT and Δ CDC14- Com strains (Figures 8E,F ). All these data illustrated that AflCDC14 of A. flavus is important for crop seeds pathogenicity.…”

“…Amylase was considered to be associated with pathogenicity in Aspergillus spp . (Alam and Kelly, 2017 ; Li et al, 2017 ). Therefore, it is likely that the lower amylase activities may contribute to reduced virulence in the Δ CDC14 mutant.…”

Carbon Catabolite Repression in Filamentous Fungi

“…In most fungal species, the zinc finger transcription factor CreA/CRE1/Mig1 mediates different aspects of CCR [ 5 , 80 , 81 , 82 ]. CreA has been identified in many filamentous fungi such as Metarhizium anisopliae , Sclerotinia sclerotiorum , B. cinerea , Neurospora crassa and Cochliobolus carbonum [ 83 , 84 , 85 ].…”

“…CreC has a regulatory mechanism in multicellular eukaryotes, which is suggested by the presence of CreB and CreC homologues in mouse and humans but not in S. cerevisiae [ 81 , 142 ]. Co-immunoprecipitation experiments have shown that CreB and CreC proteins function together as a complex during repression or derepression condition.…”