The induction of alpha-amylase by starch in Aspergillus oryzae: evidence for controlled mRNA expression.
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.
D000818:Animals; D001230:Aspergillus / Q000201:enzymology*; D001236:Aspergillus oryzae / Q000187:drug effects / Q000201:enzymology*; D004790:Enzyme Induction; D007700:Kinetics; D008970:Molecular Weight; D011061:Poly A / Q000235:genetics; D014176:Protein Biosynthesis; D012313:RNA / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D013213:Starch / Q000494:pharmacology*; D000516:alpha-Amylases / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification
D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D013213:Starch; D000516:alpha-Amylases