The induction of α-amylase by starch in Aspergillus oryzae: evidence for controlled mRNA expression

Abstract

The induction of alpha-amylase by starch has been studied in the filamentous fungus Aspergillus oryzae. Low levels of alpha-amylase activity were found in both intracellular and extracellular samples from glucose-grown cultures. However, alpha-amylase activity increased when starch was the sole carbon source. The intracellular enzyme activity was induced by a factor of approximately 6.5, while the extracellular activity increased 20-fold over that found in the glucose-grown cultures. Regardless of the carbon source or cellular location, the molecular weight of the active protein was 52 500 +/- 1800 and only this protein reacted with antibodies specific for alpha-amylase. A parallel study of the in vitro translated proteins directed by poly(A)+ RNA fractions indicated a presumptive alpha-amylase with a similar isoelectric point but with a molecular weight of approximately 54 000. This protein was most prevalent using RNA from early, exponentially growing cultures in starch medium. Immunoprecipitation data indicate that the abundance of alpha-amylase transcripts decreases dramatically after the first 12 h, reflecting an initial transcription control for the expression of this enzyme.

3 Genetic Transfer Applied to Traditional Sake Brewing

“…Ethidium bromide staining showed that almost the same amounts of RNA were present in each sample. This result confirmed that the production of T AA is controlled at a transcriptional level, consistent with the result from an in vitro translation experiment (Erratt et al, 1984).…”

Molecular Cloning and Characterization of an α-Amylase fromPichia burtonii15-1

“…5) Of the 300 -amylases known to date, Takaamylase A (TAA), secreted by Aspergillus oryzae, is one of the best studied in terms of catalytic and gene regulatory functions. [6][7][8][9][10][11][12] TAA is also the first -amylase to have its three dimensional structure determined by Xray diffraction. 13) The bioconversion of starch into ethanol is a two-step process: the first step is saccharification, where starch is converted into sugar by an amylolytic microorganism or enzymes such as -amylase and glucoamylase, and second step is fermentation, where sugar is converted into ethanol, mostly by yeasts.…”

Expression and regulation of glucoamylase from the yeast Schwanniomyces castellii

“…The combined information from these experiments allows us to hypothesize the genesis of the 146-kDa extracellular glucoamylase. As in previous work on the a-amylase of Aspergillus oryzae (8,11) and cellulase of Schizophyllum commune (37,38), there is no doubt that expression of glucoamylase is highly regulated in response to its source of carbohydrate and that this regulation is primarily at the level of mRNA transcription and stability. The immunoprecipitation of the glucoamylase-related translation product made in a rabbit reticulocyte cell-free system revealed that the nascent glucoamylase precursor is approximately 120 kDa (±+7%) in size.…”