Identification of a permease gene involved in lactose utilisation in Aspergillus nidulans

E. Fekete, L. Karaffa, Bernhard Seiboth, Éva Fekete, Christian P. Kubicek, M. Flipphi

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Lactose is intracellularly hydrolysed by Aspergillus nidulans. Classical mutation mapping data and the physical characteristics of the previously purified glycosyl hydrolase facilitated identification of the clustered, divergently transcribed intracellular β-galactosidase (bgaD) and lactose permease (lacpA) genes. At the transcript level, bgaD and lacpA were coordinately expressed in response to d-galactose, lactose or l-arabinose, while no transcription was detectable in the additional presence of glucose. In contrast, creA loss-of-function mutants derepressed for both genes to a considerable extent (even) under non-inducing or repressing growth conditions. Lactose- and d-galactose induction nevertheless occurred only in the absence of glucose, indicating a regulatory role for CreA-independent repression. Remarkably, bgaD deletion mutants grew normal on lactose. In contrast, lacpA deletants grew at a much slower rate in lactose liquid medium than wild-type while strains that carried more than one copy of lacpA grew faster, showing that transport is the limiting step in lactose catabolism. The effect of lacpA gene deletion on lactose uptake was exacerbated at lower substrate concentrations, evidence for the existence of a second transport system with a lower affinity for this disaccharide in A. nidulans.

Original languageEnglish
Pages (from-to)415-425
Number of pages11
JournalFungal Genetics and Biology
Volume49
Issue number6
DOIs
Publication statusPublished - Jun 2012

Fingerprint

Aspergillus nidulans
Membrane Transport Proteins
Lactose
Genes
Galactose
Galactosidases
Glucose
Arabinose
Disaccharides
Gene Deletion
Hydrolases
lactose permease
Mutation
Growth

Keywords

  • Gene cluster
  • Intracellular β-galactosidase
  • Lactose catabolism
  • Lactose permease
  • Multi-component lactose uptake
  • Regulation of transcription

ASJC Scopus subject areas

  • Genetics
  • Microbiology

Cite this

Identification of a permease gene involved in lactose utilisation in Aspergillus nidulans. / Fekete, E.; Karaffa, L.; Seiboth, Bernhard; Fekete, Éva; Kubicek, Christian P.; Flipphi, M.

In: Fungal Genetics and Biology, Vol. 49, No. 6, 06.2012, p. 415-425.

Research output: Contribution to journalArticle

Fekete, E. ; Karaffa, L. ; Seiboth, Bernhard ; Fekete, Éva ; Kubicek, Christian P. ; Flipphi, M. / Identification of a permease gene involved in lactose utilisation in Aspergillus nidulans. In: Fungal Genetics and Biology. 2012 ; Vol. 49, No. 6. pp. 415-425.
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