An inhibitory effect of the sequence-conserved upstream open-reading frame on the translation of the main open-reading frame of HsfB1 transcripts in Arabidopsis

Plant Cell Environ. 2012 Nov;35(11):2014-30. doi: 10.1111/j.1365-3040.2012.02533.x. Epub 2012 May 31.

Abstract

Plants have as many as 20 heat shock factors (Hsfs) grouped into three classes, A, B and C, based on sequence similarity and modular structures. Through screening for cell death-inducing factor(s) in Nicotiana benthamiana, we identified Arabidopsis HsfB2b and thus subjected all other members of Arabidopsis Hsf class B (HsfB1, HsfB2a, HsfB2b, HsfB3 and HsfB4) to the same cell death assay. When expressed in N. benthamiana leaves, only HsfB1 and HsfB2b elicited mild cell death. Simultaneously we found that HsfB1 has a post-transcriptional control mechanism, in which a sequence-conserved upstream open-reading frame (sc-uORF) is involved. The known repressor function of the respective HsfBs was confirmed and the difference in cell death-inducing activity of HsfBs was explained by the fact that HsfB1 and HsfB2b are transcriptional repressors but the others are not. Indeed, the cell death symptom by HsfB1 and HsfB2b required not only their repression activity but also their nuclear localization activity. HsfB1 expression was drastically and transiently induced by heat shock (HS) and the intactness of sc-uORF was required for its HS response. Based on the results, the physiological significance of cell death-inducing activity of HsfB1 and HsfB2b and the sc-uORF in the HsfB1 transcript during HS response is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Apoptosis / genetics
  • Arabidopsis / genetics*
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism
  • Conserved Sequence
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Glucuronidase / analysis
  • Green Fluorescent Proteins / analysis
  • Heat Shock Transcription Factors
  • Heat-Shock Proteins / genetics*
  • Heat-Shock Proteins / metabolism
  • Molecular Sequence Data
  • Nuclear Localization Signals
  • Onions / genetics
  • Open Reading Frames
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Protein Biosynthesis*
  • RNA, Messenger / metabolism*
  • RNA, Plant / metabolism*
  • Recombinant Fusion Proteins / analysis
  • Regulatory Sequences, Nucleic Acid / physiology
  • Sequence Alignment
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism

Substances

  • Arabidopsis Proteins
  • DNA-Binding Proteins
  • HSFB1 protein, Arabidopsis
  • Heat Shock Transcription Factors
  • Heat-Shock Proteins
  • Nuclear Localization Signals
  • Plant Proteins
  • RNA, Messenger
  • RNA, Plant
  • Recombinant Fusion Proteins
  • Transcription Factors
  • Green Fluorescent Proteins
  • Glucuronidase