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The function of CreA, the carbon catabolite repressor of Aspergillus nidulans , is regulated at the transcriptional and post‐transcriptional level
Author(s) -
Strauss Joseph,
Horvath Henny K.,
Abdallah Basem M.,
Kindermann Johanna,
Mach Robert L.,
Kubicek Christian P.
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01341.x
Subject(s) - catabolite repression , aspergillus nidulans , repressor , biology , biochemistry , transcriptional regulation , northern blot , gene expression , regulation of gene expression , mutant , gene , microbiology and biotechnology
The creA gene of A. nidulans encodes a wide‐domain regulatory protein mediating carbon catabolite repression. Northern blot analysis of creA mRNA revealed a complex expression profile: the addition of monosaccharides to a carbon‐starved culture of A. nidulans provoked a strong transient stimulation of creA transcript formation within a few minutes. In the case of repressing carbon sources, creA mRNA levels were subsequently downregulated, whereas the high creA mRNA levels were maintained in a creA mutant strain and in the presence of derepressing monosaccharides. A high creA transcript level is essential to achieve carbon catabolite repression and is dependent on glucose transport and, at least partially, on the creB gene product. Subsequent downregulation of creA mRNA levels, on the other hand, is typical of carbon catabolite repression and requires a functional CreA recognition site in the creA promoter (and thus involves autoregulation) and formation of glucose‐6‐phosphate. Despite the presence of continuing high transcript levels of creA in the presence of derepressing carbohydrates, EMSA demonstrated the presence of only low levels of a CreA–DNA complex in respective cell‐free extracts. Upon transfer of carbon catabolite derepressed mycelia to catabolite‐repressing conditions, a CreA–DNA complex is formed, and this process is dependent on de novo protein synthesis.