Xylose triggers reversible phosphorylation of XlnR, the fungal transcriptional activator of xylanolytic and cellulolytic genes in Aspergillus oryzae

Biosci Biotechnol Biochem. 2011;75(5):953-9. doi: 10.1271/bbb.100923. Epub 2011 May 20.

Abstract

XlnR is a transcription factor that mediates D-xylose-triggered induction of xylanolytic and cellulolytic genes in Aspergillus. In order to clarify the molecular mechanisms underlying XlnR-mediated induction, Aspergillus oryzae XlnR was fused with the c-myc tag and examined by Western blotting. Phosphate-affinity SDS-PAGE revealed that XlnR was present as a mixture of variously phosphorylated forms in the absence of D-xylose, and that D-xylose triggered additional phosphorylation of the protein. D-Xylose-triggered phosphorylation was a rapid process occurring within 5 min prior to the accumulation of xynG2 mRNA, and removal of D-xylose caused slow dephosphorylation, leading to less-phosphorylated forms. At 30 min after removal, the phosphorylation status was almost identical to that in the absence of D-xylose, and the level of xynG2 mRNA started to decrease. These results indicate that XlnR is highly phosphorylated when it is active in transactivation, implying that D-xylose-triggered reversible phosphorylation controls XlnR activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspergillus oryzae / drug effects
  • Aspergillus oryzae / genetics*
  • Aspergillus oryzae / metabolism
  • Cellulose / metabolism*
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Glucose / pharmacology
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-myc / genetics
  • Sugar Alcohols / pharmacology
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcription, Genetic / drug effects
  • Transcriptional Activation* / drug effects
  • Xylans / metabolism*
  • Xylose / pharmacology*

Substances

  • Fungal Proteins
  • Proto-Oncogene Proteins c-myc
  • Sugar Alcohols
  • Trans-Activators
  • XlnR protein, Aspergillus
  • Xylans
  • Cellulose
  • Xylose
  • Glucose