UNASSIGNED: @entity11150 is an important industrial fungus expressing a broad spectrum of pectinolytic genes. The main constituent of pectin, @entity16147 ( @entity6987 ), is degraded into @entity17130 (GA) by the combined activity of endo- and exo-polygalacturonases some of which are specifically induced by GA. The regulatory mechanisms that control the expression of genes encoding @entity6987 -degrading enzymes are not well understood. Based on available genome-wide expression profiles from literature, we selected five genes that were specifically induced by GA. These genes include three exo-polygalacturonases (pgaX, pgxB and pgxC), a GA transporter (gatA), and an intracellular enzyme involved in GA metabolism (gaaB). These five genes contain a conserved motif (5'-TCCNCCAAT-3') in their promoter regions, which we named GARE ( @entity17130 -responsive element). Promoter deletion studies and site-directed mutagenesis of the conserved motif of the pgaX gene showed that the conserved element is required for GA-mediated induction. A set of promoter reporter strains was constructed by fusing the promoter region of the five above-mentioned genes to the amdS reporter gene. Expression of the amdS gene is quantitatively correlated with ability to utilise @entity14941 as an N-source, hence higher expression of amdS improves growth of the strain on @entity14941 and therefore can be used as an in vivo reporter for gene expression. Growth analysis of the reporter strains indicated that four genes (pgaX, pgxB, pgxC, and gatA) are specifically induced by GA. The in vivo promoter reporter strains were also used to monitor @entity505 catabolite repression control. Except for gaaB, all promoter-reporter genes analysed were repressed by @entity413 in a @entity413 concentration-dependent way. Interestingly, the strength of @entity413 repression was different for the tested promoters. CreA is important in mediating @entity505 catabolite repression as deletion of the creA gene in the reporter strains abolished @entity505 catabolite repression for most promoters. Interestingly, the pgxC promoter was still repressed by @entity413 even in the creA null background, suggesting a role for alternative repression mechanisms. Finally, we showed that low concentrations of GA are required to induce gene expression of pgaX, pgxB, and pgxC even under derepressing conditions. The results obtained are consistent with a model in which a GA-specific transcription factor is activated by GA or a GA-derivative, which binds to the conserved motif, possibly in combination with the HAP-complex, to drive GA-specific gene expression.

The interaction of induction and repression mechanisms in the regulation of XXXX -induced genes in @entity11150 .

@entity6987 :: ('MESH:D011454', 'Chemical') :: ['PGA'] @entity17130 :: ('MESH:C007819', 'Chemical') :: ['galacturonic acid'] @entity14941 :: ('MESH:C030686', 'Chemical') :: ['acetamide'] @entity11150 :: ('5061', 'Species') :: ['Aspergillus niger'] @entity16147 :: ('MESH:C003181', 'Chemical') :: ['polygalacturonic acid'] @entity505 :: ('MESH:D002244', 'Chemical') :: ['carbon'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['glucose']
@entity17130 :: (MESH:C007819,Chemical) :: ['galacturonic acid']
