title: Transcription factor IIB (TFIIB)-related protein (pBrp), a plant-specific member of the TFIIB-related protein family.
abstract: 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.
authors.affiliation: Laboratoire de Génétique Moléculaire des Plantes, UMR5575, 38041 Grenoble Cedex 9, France. lagrange@univ-perp.fr
authors.forename: Thierry
authors.initials: T
authors.lastname: Lagrange
authors.forename: Mohamed-Ali
authors.initials: MA
authors.lastname: Hakimi
authors.forename: Dominique
authors.initials: D
authors.lastname: Pontier
authors.forename: Florence
authors.initials: F
authors.lastname: Courtois
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Alcaraz
authors.forename: Didier
authors.initials: D
authors.lastname: Grunwald
authors.forename: Eric
authors.initials: E
authors.lastname: Lam
authors.forename: Silva
authors.initials: S
authors.lastname: Lerbs-Mache
mesh_terms: 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
chemical_list: 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