scholarly journals Upstream binding factor stabilizes Rib 1, the TATA-binding-protein-containing Xenopus laevis RNA polymerase I transcription factor, by multiple protein interactions in a DNA-independent manner.

1996 ◽  
Vol 16 (10) ◽  
pp. 5572-5578 ◽  
Author(s):  
M Bodeker ◽  
C Cairns ◽  
B McStay
Keyword(s):  
Xenopus Laevis ◽  
Rna Polymerase ◽  
Protein Interactions ◽  
Tata Binding Protein ◽  
Rna Polymerase I ◽  
Independent Manner ◽  
Multiple Protein ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Polymerase I

Initiation of RNA polymerase I transcription in Xenopus laevis requires Rib 1 and upstream binding factor (UBF). UBF and Rib 1 combine to form a stable transcription complex on the Xenopus ribosomal gene promoter. Here we show that Rib 1 comprises TATA-binding protein (TBP) and TBP-associated factor components. Thus, Rib 1 is the Xenopus equivalent of mammalian SL 1. In contrast to SL 1, Rib 1 is an unstable complex that readily dissociates into TBP and associated components. We identify a novel function for UBF in stabilizing Rib 1 by multiple protein interactions. This stabilization occurs in solution in a DNA-independent manner. These results may partially explain the difference in UBF requirement between Xenopus and mammalian systems.

scholarly journals The species-specific RNA polymerase I transcription factor SL-1 binds to upstream binding factor.

1996 ◽  
Vol 16 (2) ◽  
pp. 557-563 ◽  
Author(s):  
W M Hempel ◽  
A H Cavanaugh ◽  
R D Hannan ◽  
L Taylor ◽  
L I Rothblum
Keyword(s):  
Rna Polymerase ◽  
Binding Protein ◽  
Sodium Dodecyl ◽  
Tata Binding Protein ◽  
Rna Polymerase I ◽  
Rrna Genes ◽  
Cell Extracts ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Polymerase I

Transcription of the 45S rRNA genes is carried out by RNA polymerase I and at least two trans-acting factors, upstream binding factor (UBF) and SL-1. We have examined the hypothesis that SL-1 and UBF interact. Coimmunoprecipitation studies using an antibody to UBF demonstrated that TATA-binding protein, a subunit of SL-1, associates with UBF in the absence of DNA. Inclusion of the detergents sodium dodecyl sulfate and deoxycholate disrupted this interaction. In addition, partially purified UBF from rat cell nuclear extracts and partially purified SL-1 from human cells coimmunoprecipitated with the anti-UBF antibody after mixing, indicating that the UBF-SL-1 complex can re-form. Treatment of UBF-depleted extracts with the anti-UBF antibody depleted the extracts of SL-1 activity only if UBF was added to the extract prior to the immunodepletion reaction. Furthermore, SL-1 activity could be recovered in the immunoprecipitate. Interestingly, these immunoprecipitates did not contain RNA polymerase I, as a monospecific antibody to the 194-kDa subunit of RNA polymerase I failed to detect that subunit in the immunoprecipitates. Treatment of N1S1 cell extracts with the anti-UBF antibody depleted the extracts of SL-1 activity but not TFIIIB activity, suggesting that the binding of UBF to SL-1 is specific and not solely mediated by an interaction between UBF and TATA-binding protein, which is also a component of TFIIIB. These data provide evidence that UBF and SL-1 interact.

scholarly journals Modifications of both selectivity factor and upstream binding factor contribute to poliovirus-mediated inhibition of RNA polymerase I transcription

2005 ◽  
Vol 86 (8) ◽  
pp. 2315-2322 ◽  
Author(s):  
Rajeev Banerjee ◽  
Mary K. Weidman ◽  
Sonia Navarro ◽  
Lucio Comai ◽  
Asim Dasgupta
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase I ◽  
Rrna Synthesis ◽  
Selectivity Factor ◽  
Pol I ◽  
Binding Factor ◽  
Infected Cells ◽  
Upstream Binding Factor ◽  
Polymerase I

Soon after infection, poliovirus (PV) shuts off host-cell transcription, which is catalysed by all three cellular RNA polymerases. rRNA constitutes more than 50 % of all cellular RNA and is transcribed from rDNA by RNA polymerase I (pol I). Here, evidence has been provided suggesting that both pol I transcription factors, SL-1 (selectivity factor) and UBF (upstream binding factor), are modified and inactivated in PV-infected cells. The viral protease 3Cpro appeared to cleave the TATA-binding protein-associated factor 110 (TAF110), a subunit of the SL-1 complex, into four fragments in vitro. In vitro protease-cleavage assays using various mutants of TAF110 and purified 3Cpro indicated that the Q265G266 and Q805G806 sites were cleaved by 3Cpro. Both SL-1 and UBF were depleted in PV-infected cells and their disappearance correlated with pol I transcription inhibition. rRNA synthesis from a template containing a human pol I promoter demonstrated that both SL-1 and UBF were necessary to restore pol I transcription fully in PV-infected cell extracts. These results suggested that both SL-1 and UBF are transcriptionally inactivated in PV-infected HeLa cells.

scholarly journals TBP-TAF Complex SL1 Directs RNA Polymerase I Pre-initiation Complex Formation and Stabilizes Upstream Binding Factor at the rDNA Promoter

2005 ◽  
Vol 280 (33) ◽  
pp. 29551-29558 ◽  
Author(s):  
J. Karsten Friedrich ◽  
Kostya I. Panov ◽  
Pavel Cabart ◽  
Jackie Russell ◽  
Joost C. B. M. Zomerdijk
Keyword(s):  
Complex Formation ◽  
Rna Polymerase ◽  
Rna Polymerase I ◽  
Initiation Complex ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Polymerase I

scholarly journals The RNA polymerase I transactivator upstream binding factor requires its dimerization domain and high-mobility-group (HMG) box 1 to bend, wrap, and positively supercoil enhancer DNA.

1994 ◽  
Vol 14 (10) ◽  
pp. 6476-6488 ◽  
Author(s):  
C D Putnam ◽  
G P Copenhaver ◽  
M L Denton ◽  
C S Pikaard
Keyword(s):  
Rna Polymerase ◽  
High Mobility ◽  
Rna Polymerase I ◽  
High Mobility Group ◽  
Dna Ligase ◽  
Dimerization Domain ◽  
Hmg Box ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Polymerase I

Upstream binding factor (UBF) is an important transactivator of RNA polymerase I and is a member of a family of proteins that contain nucleic acid binding domains named high-mobility-group (HMG) boxes because of their similarity to HMG chromosomal proteins. UBF is a highly sequence-tolerant DNA-binding protein for which no binding consensus sequence has been identified. Therefore, it has been suggested that UBF may recognize preformed structural features of DNA, a hypothesis supported by UBF's ability to bind synthetic DNA cruciforms, four-way junctions, and even tRNA. We show here that full-length UBF can also bend linear DNA to mediate circularization of probes as small as 102 bp in the presence of DNA ligase. Longer probes in the presence of UBF become positively supercoiled when ligated, suggesting that UBF wraps the DNA in a right-handed direction, opposite the direction of DNA wrapping around a nucleosome. The dimerization domain and HMG box 1 are necessary and sufficient to circularize short probes and supercoil longer probes in the presence of DNA ligase. UBF's sequence tolerance coupled with its ability to bend and wrap DNA makes UBF an unusual eukaryotic transcription factor. However, UBF's ability to bend DNA might explain how upstream and downstream rRNA gene promoter domains interact. UBF-induced DNA wrapping could also be a mechanism by which UBF counteracts histone-mediated gene repression.

The RNA polymerase I transactivator upstream binding factor requires its dimerization domain and high-mobility-group (HMG) box 1 to bend, wrap, and positively supercoil enhancer DNA

1994 ◽  
Vol 14 (10) ◽  
pp. 6476-6488
Author(s):  
C D Putnam ◽  
G P Copenhaver ◽  
M L Denton ◽  
C S Pikaard
Keyword(s):  
Rna Polymerase ◽  
High Mobility ◽  
Rna Polymerase I ◽  
High Mobility Group ◽  
Dna Ligase ◽  
Dimerization Domain ◽  
Hmg Box ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Polymerase I

Upstream binding factor (UBF) is an important transactivator of RNA polymerase I and is a member of a family of proteins that contain nucleic acid binding domains named high-mobility-group (HMG) boxes because of their similarity to HMG chromosomal proteins. UBF is a highly sequence-tolerant DNA-binding protein for which no binding consensus sequence has been identified. Therefore, it has been suggested that UBF may recognize preformed structural features of DNA, a hypothesis supported by UBF's ability to bind synthetic DNA cruciforms, four-way junctions, and even tRNA. We show here that full-length UBF can also bend linear DNA to mediate circularization of probes as small as 102 bp in the presence of DNA ligase. Longer probes in the presence of UBF become positively supercoiled when ligated, suggesting that UBF wraps the DNA in a right-handed direction, opposite the direction of DNA wrapping around a nucleosome. The dimerization domain and HMG box 1 are necessary and sufficient to circularize short probes and supercoil longer probes in the presence of DNA ligase. UBF's sequence tolerance coupled with its ability to bend and wrap DNA makes UBF an unusual eukaryotic transcription factor. However, UBF's ability to bend DNA might explain how upstream and downstream rRNA gene promoter domains interact. UBF-induced DNA wrapping could also be a mechanism by which UBF counteracts histone-mediated gene repression.

A role for upstream binding factor in organizing ribosomal gene chromatin

2006 ◽  
Vol 73 ◽  
pp. 77-84 ◽  
Author(s):  
Jane E. Wright ◽  
Christine Mais ◽  
José-Luis Prieto ◽  
Brian McStay
Keyword(s):  
Nucleolar Organizer ◽  
Ribosomal Gene ◽  
Rna Polymerase I ◽  
Nucleolar Organizer Regions ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Acrocentric Chromosomes ◽  
Polymerase I ◽  
Secondary Constrictions ◽  
Active Nors

Human ribosomal genes are located in NORs (nucleolar organizer regions) on the short arms of acrocentric chromosomes. During metaphase, previously active NORs appear as prominent chromosomal features termed secondary constrictions, which are achromatic in chromosome banding and positive in silver staining. The architectural RNA polymerase I transcription factor UBF (upstream binding factor) binds extensively across the ribosomal gene repeat throughout the cell cycle. Evidence that UBF underpins NOR structure is provided by an examination of cell lines in which large arrays of a heterologous UBF binding sequences are integrated at ectopic sites on human chromosomes. These arrays efficiently recruit UBF even to sites outside the nucleolus, and during metaphase form novel silver-stainable secondary constrictions, termed pseudo-NORs, that are morphologically similar to NORs.

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