Mutations in ribosomal proteins, RPL4 and RACK1, suppress the phenotype of a thermospermine-deficient mutant of Arabidopsis thaliana

PLoS One. 2015 Jan 27;10(1):e0117309. doi: 10.1371/journal.pone.0117309. eCollection 2015.

Abstract

Thermospermine acts in negative regulation of xylem differentiation and its deficient mutant of Arabidopsis thaliana, acaulis5 (acl5), shows excessive xylem formation and severe dwarfism. Studies of two dominant suppressors of acl5, sac51-d and sac52-d, have revealed that SAC51 and SAC52 encode a transcription factor and a ribosomal protein L10 (RPL10), respectively, and these mutations enhance translation of the SAC51 mRNA, which contains conserved upstream open reading frames in the 5' leader. Here we report identification of SAC53 and SAC56 responsible for additional suppressors of acl5. sac53-d is a semi-dominant allele of the gene encoding a receptor for activated C kinase 1 (RACK1) homolog, a component of the 40S ribosomal subunit. sac56-d represents a semi-dominant allele of the gene for RPL4. We show that the GUS reporter activity driven by the CaMV 35S promoter plus the SAC51 5' leader is reduced in acl5 and restored by sac52-d, sac53-d, and sac56-d as well as thermospermine. Furthermore, the SAC51 mRNA, which may be a target of nonsense-mediated mRNA decay, was found to be stabilized in these ribosomal mutants and by thermospermine. These ribosomal proteins are suggested to act in the control of uORF-mediated translation repression of SAC51, which is derepressed by thermospermine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Gene Expression
  • Genes, Dominant
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • RNA Stability
  • Receptors for Activated C Kinase
  • Receptors, Cell Surface / genetics*
  • Receptors, Cell Surface / metabolism
  • Ribosomal Protein L10
  • Ribosomal Proteins / genetics*
  • Ribosomal Proteins / metabolism

Substances

  • Arabidopsis Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • RACK1 protein, Arabidopsis
  • Receptors for Activated C Kinase
  • Receptors, Cell Surface
  • Ribosomal Proteins
  • SAC51 protein, Arabidopsis
  • ribosomal protein L10, Arabidopsis
  • ribosomal protein L4

Grants and funding

This work was supported in part by Grants-in-Aid for Scientific Research No. 22370021 and No. 26113516 from the Japan Society for the Promotion of Science (JSPS) and a grant from the Ryobi-Teien Memorial Foundation to TT. JIK was a recipient of a JSPS research fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.