title: Distinct mechanism of activation of two transcription factors, AmyR and MalR, involved in amylolytic enzyme production in Aspergillus oryzae.
abstract: The production of amylolytic enzymes in Aspergillus oryzae is induced in the presence of starch or maltose, and two Zn2Cys6-type transcription factors, AmyR and MalR, are involved in this regulation. AmyR directly regulates the expression of amylase genes, and MalR controls the expression of maltose-utilizing (MAL) cluster genes. Deletion of malR gene resulted in poor growth on starch medium and reduction in α-amylase production level. To elucidate the activation mechanisms of these two transcription factors in amylase production, the expression profiles of amylases and MAL cluster genes under carbon catabolite derepression condition and subcellular localization of these transcription factors fused with a green fluorescent protein (GFP) were examined. Glucose, maltose, and isomaltose induced the expression of amylase genes, and GFP-AmyR was translocated from the cytoplasm to nucleus after the addition of these sugars. Rapid induction of amylase gene expression and nuclear localization of GFP-AmyR by isomaltose suggested that this sugar was the strongest inducer for AmyR activation. In contrast, GFP-MalR was constitutively localized in the nucleus and the expression of MAL cluster genes was induced by maltose, but not by glucose or isomaltose. In the presence of maltose, the expression of amylase genes was preceded by MAL cluster gene expression. Furthermore, deletion of the malR gene resulted in a significant decrease in the α-amylase activity induced by maltose, but had apparently no effect on the expression of α-amylase genes in the presence of isomaltose. These results suggested that activation of AmyR and MalR is regulated in a different manner, and the preceding activation of MalR is essential for the utilization of maltose as an inducer for AmyR activation.
authors.affiliation: Laboratory of Bioindustrial Genomics, Department of Bioindustrial Informatics and Genomics, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, 981-8555, Japan.
authors.forename: Kuta
authors.initials: K
authors.lastname: Suzuki
authors.forename: Mizuki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Yui
authors.initials: Y
authors.lastname: Konno
authors.forename: Takanori
authors.initials: T
authors.lastname: Ichikawa
authors.forename: Sakurako
authors.initials: S
authors.lastname: Ichinose
authors.forename: Sachiko
authors.initials: S
authors.lastname: Hasegawa-Shiro
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shintani
authors.forename: Katsuya
authors.initials: K
authors.lastname: Gomi
mesh_terms: D000681:Amylases / Q000096:biosynthesis* / Q000235:genetics; D001236:Aspergillus oryzae / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D002467:Cell Nucleus / Q000737:chemistry; D003470:Culture Media / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D017930:Genes, Reporter; D005947:Glucose / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D007534:Isomaltose / Q000378:metabolism; D008320:Maltose / Q000378:metabolism; D005810:Multigene Family; D013213:Starch / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D003470:Culture Media; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D007534:Isomaltose; D008320:Maltose; D013213:Starch; D000681:Amylases; D005947:Glucose