Transcription factor IIB (TFIIB)-related protein (pBrp), a plant-specific member of the TFIIB-related protein family.
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.
Lagrange
Thierry
T
Laboratoire de Génétique Moléculaire des Plantes, UMR5575, 38041 Grenoble Cedex 9, France. lagrange@univ-perp.fr
Hakimi
Mohamed-Ali
MA
Pontier
Dominique
D
Courtois
Florence
F
Alcaraz
Jean Pierre
JP
Grunwald
Didier
D
Lam
Eric
E
Lerbs-Mache
Silva
S
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D005075:Biological Evolution; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007976:Leupeptins / Q000494:pharmacology; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism; D005810:Multigene Family; D018087:Plastids / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D035581:Transcription Factor TFIIB / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D009097:Multienzyme Complexes; D035581:Transcription Factor TFIIB; D014157:Transcription Factors; C474201:transcription factor IIB-related protein, Arabidopsis; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde