Open AccessTranscription Factor IIB (TFIIB)-Related Protein (pBrp), a Plant-Specific Member of the TFIIB-Related Protein Family
Author(s) -
Thierry Lagrange,
MohamedAli Hakimi,
Dominique Pontier,
Florence Courtois,
Jean-Pierre Alcaraz,
Didier Grünwald,
Eric Lam,
Silva Lerbs-Mache
Publication year - 2003
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.23.9.3274-3286.2003
Subject(s) - biology , transcription factor ii b , transcription factor , transcription factor ii a , microbiology and biotechnology , eif4ebp1 , genetics , transcription preinitiation complex , taf4 , gene , promoter , gene expression , messenger rna , translation (biology)
Although it is now well documented that metazoans have evolved general transcription factor (GTF) variants to regulate their complex patterns of gene expression, there is so far no information regarding the existence of specific GTFs in plants. Here we report the characterization of a ubiquitously expressed gene that encodes a bona fide novel transcription factor IIB (TFIIB)-related protein in Arabidopsis thaliana. We have shown that this protein is the founding member of a plant-specific TFIIB-related protein family named pBrp (for plant-specific TFIIB-related protein). Surprisingly, in contrast to common GTFs that are localized in the nucleus, the bulk of pBrp proteins are bound to the cytoplasmic face of the plastid envelope, suggesting an organelle-specific function for this novel class of TFIIB-related protein. We show that pBrp proteins harbor conditional proteolytic signals that can target these proteins for rapid turnover by the proteasome-mediated protein degradation pathway. Interestingly, under conditions of proteasome inhibition, pBrp proteins accumulate in the nucleus. Together, our results suggest a possible involvement of these proteins in an intracellular signaling pathway between plastids and the nucleus. Our data provide the first evidence for an organelle-related evolution of the eukaryotic general transcription machinery.