Functional characterization of the plant ubiquitin regulatory X (UBX) domain-containing protein AtPUX7 in Arabidopsis thaliana

Gene. 2013 Sep 10;526(2):299-308. doi: 10.1016/j.gene.2013.05.056. Epub 2013 Jun 4.

Abstract

p97/CDC48 is a major AAA-ATPase that acts in many cellular events such as ubiquitin-dependent degradation and membrane fusion. Its specificity depends on a set of adaptor proteins, most of them containing the ubiquitin regulatory X (UBX) domain. Using a differential hybridization system, we isolated a UBX-containing protein that is expressed during the early phase of male gametophyte development in the crop Brassica napus and isolated and characterized its closest Arabidopsis thaliana homolog, AtPUX7. The AtPUX7 gene is expressed broadly in both the sporophyte and gametophyte due to regulation inferred by its first intron. The subcellular localization of AtPUX7 was assigned mainly to the nucleus in both the sporophyte and in pollen, mirroring the AAA-ATPase AtCDC48A localization. Furthermore, AtPUX7 interacts specifically with AtCDC48A in yeast as well as in planta in the nucleus. This interaction was mediated through the AtPUX7 UBX domain, which is located at the protein C-terminus, while an N-terminal UBA domain mediated its interaction with ubiquitin. Consistent with those results, a yeast-three hybrid analysis showed that AtPUX7 can act as a bridge between AtCDC48A and ubiquitin, suggesting a role in targeted protein degradation. It is likely that AtPUX7 acts redundantly with other members of the Arabidopsis PUX family because a null Atpux7-1 mutant does not display obvious developmental defects.

Keywords: AAA-ATPase; ATPase associated with diverse cellular activities; Arabidopsis thaliana; ER; ERAD; Gametophyte; IME; PUX; UBA; UBX; UBX-containing protein; UIM; UPS; Ub; endoplasmic reticulum; endoplasmic reticulum-associated protein degradation; intron-mediated enhancement; p97/VCP/CDC48; plant ubiquitin regulatory X domain-containing protein; ubiquitin; ubiquitin regulatory X; ubiquitin-associated; ubiquitin-interacting motif; ubiquitin/26S proteasome system.

MeSH terms

  • ATPases Associated with Diverse Cellular Activities
  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Brassicaceae / genetics
  • Brassicaceae / metabolism
  • Carrier Proteins / metabolism*
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / metabolism
  • Cell Nucleus / metabolism
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism
  • Gene Expression
  • Gene Expression Regulation, Plant
  • Gene Order
  • Homeodomain Proteins / chemistry
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Intracellular Signaling Peptides and Proteins
  • Introns
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Pollen / genetics
  • Pollen / metabolism
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Transport
  • Sequence Alignment
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Ubiquitin / metabolism

Substances

  • Arabidopsis Proteins
  • Carrier Proteins
  • Cell Cycle Proteins
  • Drosophila Proteins
  • Homeodomain Proteins
  • Intracellular Signaling Peptides and Proteins
  • PUX7 protein, Arabidopsis
  • Transcription Factors
  • Ubiquitin
  • Ubx protein, Drosophila
  • ATPases Associated with Diverse Cellular Activities
  • CDC48A protein, Arabidopsis