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

• Published in: Plant, cell and environment cell and environment, 2012-11, Vol.35 (11), p.2014-2030
• Main Authors: ZHU, XUJUN, THALOR, SUNIL KUMAR, TAKAHASHI, YOSHIHIRO, BERBERICH, THOMAS, KUSANO, TOMONOBU
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Apoptosis - genetics; Arabidopsis; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biological and medical sciences; cell death; Conserved Sequence; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Glucuronidase - analysis; Green Fluorescent Proteins - analysis; heat shock; Heat Shock Transcription Factors; heat stress; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; leaves; Molecular Sequence Data; Nicotiana benthamiana; Nuclear Localization Signals; Onions - genetics; Open Reading Frames; Plant Proteins - genetics; Plant Proteins - metabolism; Protein Biosynthesis; Recombinant Fusion Proteins - analysis; Regulatory Sequences, Nucleic Acid - physiology; repression domain; RNA, Messenger - metabolism; RNA, Plant - metabolism; screening; Sequence Alignment; transcription factor; Transcription Factors - genetics; Transcription Factors - metabolism; transcriptional repressor
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2012.02533.x

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.