The arrestin-like protein ArtA is essential for ubiquitination and endocytosis of the UapA transporter in response to both broad-range and specific signals

Mol Microbiol. 2013 Apr;88(2):301-17. doi: 10.1111/mmi.12184. Epub 2013 Mar 12.

Abstract

We investigated the role of all arrestin-like proteins of Aspergillus nidulans in respect to growth, morphology, sensitivity to drugs and specifically for the endocytosis and turnover of the uric acid-xanthine transporter UapA. A single arrestin-like protein, ArtA, is essential for HulA(Rsp) (5) -dependent ubiquitination and endocytosis of UapA in response to ammonium or substrates. Mutational analysis showed that residues 545-563 of the UapA C-terminal region are required for efficient UapA endocytosis, whereas the N-terminal region (residues 2-123) and both PPxY motives are essential for ArtA function. We further show that ArtA undergoes HulA-dependent ubiquitination at residue Lys-343 and that this modification is critical for UapA ubiquitination and endocytosis. Lastly, we show that ArtA is essential for vacuolar turnover of transporters specific for purines (AzgA) or l-proline (PrnB), but not for an aspartate/glutamate transporter (AgtA). Our results are discussed within the frame of recently proposed mechanisms on how arrestin-like proteins are activated and recruited for ubiquitination of transporters in response to broad range signals, but also put the basis for understanding how arrestin-like proteins, such as ArtA, regulate the turnover of a specific transporter in the presence of its substrates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arrestin / genetics
  • Arrestin / metabolism*
  • Aspergillus nidulans / drug effects
  • Aspergillus nidulans / genetics
  • Aspergillus nidulans / growth & development
  • Aspergillus nidulans / metabolism
  • DNA Mutational Analysis
  • Endocytosis* / physiology
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Metabolic Networks and Pathways
  • Proline / metabolism
  • Protein Transport / physiology
  • Purines / metabolism
  • Substrate Specificity
  • Ubiquitination* / physiology
  • Vacuoles / metabolism

Substances

  • Arrestin
  • Fungal Proteins
  • Membrane Transport Proteins
  • Purines
  • UAPA protein, Aspergillus nidulans
  • Proline