scholarly journals Human TFIIIC Relieves Chromatin-Mediated Repression of RNA Polymerase III Transcription and Contains an Intrinsic Histone Acetyltransferase Activity

1999 ◽  
Vol 19 (2) ◽  
pp. 1605-1615 ◽  
Author(s):  
Tapas K. Kundu ◽  
Zhengxin Wang ◽  
Robert G. Roeder

ABSTRACT Human TFIIIC is a multisubunit factor that is essential for transcription by RNA polymerase III on tRNA and virus-associated RNA genes and initiates preinitiation complex assembly by direct recognition of promoter elements. We show that highly purified TFIIIC, at concentrations above those sufficient for transcription of naked DNA templates, effectively relieves nucleosome-mediated repression on an in vitro-reconstituted chromatin template. Highly purified TFIIIC alone can bind to the A and B boxes of a tRNA gene within a chromatin template and, further, displays a histone acetyltransferase activity that is intrinsic to at least one (and probably three) of its subunits. The possibility of a direct link between TFIIIC-dependent chromatin transcription and acetyltransferase activities is suggested by the partial loss of these activities, but not DNA transcription activity, following pretreatment of TFIIIC withp-hydroxymercuribenzoic acid.

1999 ◽  
Vol 19 (11) ◽  
pp. 7697-7704 ◽  
Author(s):  
Yng-Ju Hsieh ◽  
Tapas K. Kundu ◽  
Zhengxin Wang ◽  
Robert Kovelman ◽  
Robert G. Roeder

ABSTRACT Human transcription factor IIIC (hTFIIIC) is a multisubunit complex that directly recognizes promoter elements and recruits TFIIIB and RNA polymerase III. Here we describe the cDNA cloning and characterization of the 90-kDa subunit (hTFIIIC90) that is present within a DNA-binding subcomplex (TFIIIC2) of TFIIIC. hTFIIIC90 has no specific homology to any of the known yeast TFIIIC subunits. Immunodepletion and immunoprecipitation studies indicate that hTFIIIC90 is a bona fide subunit of TFIIIC2 and absolutely required for RNA polymerase III transcription. hTFIIIC90 shows interactions with the hTFIIIC220, hTFIIIC110, and hTFIIIC63 subunits of TFIIIC, the hTFIIIB90 subunit of TFIIIB, and the human RPC39 (hRPC39) and hRPC62 subunits of an initiation-specific subcomplex of RNA polymerase III. These interactions may facilitate both TFIIIB and RNA polymerase III recruitment to the preinitiation complex by TFIIIC. We show that hTFIIIC90 has an intrinsic histone acetyltransferase activity with a substrate specificity for histone H3.


2007 ◽  
Vol 27 (24) ◽  
pp. 8729-8738 ◽  
Author(s):  
Chih-Chi Yuan ◽  
Xinyang Zhao ◽  
Laurence Florens ◽  
Selene K. Swanson ◽  
Michael P. Washburn ◽  
...  

ABSTRACT Chromatin remodeling and histone modification are essential for eukaryotic transcription regulation, but little is known about chromatin-modifying activities acting on RNA polymerase III (Pol III)-transcribed genes. The human U6 small nuclear RNA promoter, located 5′ of the transcription start site, consists of a core region directing basal transcription and an activating region that recruits the transcription factors Oct-1 and Staf (ZNF143). Oct-1 activates transcription in part by helping recruit core binding factors, but nothing is known about the mechanisms of transcription activation by Staf. We show that Staf activates U6 transcription from a preassembled chromatin template in vitro and associates with several proteins linked to chromatin modification, among them chromodomain-helicase-DNA binding protein 8 (CHD8). CHD8 binds to histone H3 di- and trimethylated on lysine 4. It resides on the human U6 promoter as well as the mRNA IRF3 promoter in vivo and contributes to efficient transcription from both these promoters. Thus, Pol III transcription from type 3 promoters uses some of the same factors used for chromatin remodeling at Pol II promoters.


2019 ◽  
Author(s):  
Moumita Basu ◽  
Ramachandran Boopathi ◽  
Sadhan Das ◽  
Tapas K Kundu

ABSTRACTTFIIIC is a multisubunit complex that recognizes promoter elements and recruits TFIIIB and RNA polymerase III. Human TFIIIC complex possess lysine acetyltransferase activity which is critical in relieving chromatin mediated repression for RNA polymerase III-mediated transcription; two subunits of the TFIIIC complex, TFIIIC110 and TFIIIC90, were shown to acetylate H3 in vitro. Here we show that the largest and DNA binding subunit of TFIIIC complex, TFIIIC220, possesses intrinsic lysine acetyltransferase activity and acetylates histone H3K18 residue. By employing homology search we have identified the potential catalytic domain of TFIIIC220 which efficiently acetylate core histones in vitro. Point mutations at the critical residues of the identified acetyltransferase domain drastically reduces the acetyltransferase activity. Significantly, knockdown of TFIIIC220 in HepG2 cell line dramatically reduces global H3K18 acetylation level suggesting that TFIIIC220 is a crucial KAT to maintain acetylation homeostasis in the cell.


1993 ◽  
Vol 13 (5) ◽  
pp. 2655-2665 ◽  
Author(s):  
J G Howe ◽  
M D Shu

The Epstein-Barr virus-encoded small RNA (EBER) genes are transcribed by RNA polymerase III, but their transcription unit appears to contain both class II and class III promoter elements. One of these promoter element, a TATA-like box which we call the EBER TATA box, or ETAB, is located in a position typical for a class II TATA box but contains G/C residues in the normal T/A motif and a conserved thymidine doublet. Experiments using chloramphenicol acetyltransferase constructs and mutations in the TATA box of the adenovirus major late promoter showed that the ETAB promoter element does not substitute for a class II TATA box. However, when the ETAB promoter element sequence was changed to a class II TATA box consensus sequence, the EBER 2 gene was transcribed in vitro by both RNA polymerases II and III. From these results, we conclude that the ETAB promoter element is important for the exclusive transcription of the EBER 2 gene by RNA polymerase III.


1994 ◽  
Vol 14 (9) ◽  
pp. 6164-6170
Author(s):  
P P Sadhale ◽  
N A Woychik

We identified a partially sequenced Saccharomyces cerevisiae gene which encodes a protein related to the S. cerevisiae RNA polymerase II subunit, RPB7. Several lines of evidence suggest that this related gene, YKL1, encodes the RNA polymerase III subunit C25. C25, like RPB7, is present in submolar ratios, easily dissociates from the enzyme, is essential for cell growth and viability, but is not required in certain transcription assays in vitro. YKL1 has ABF-1 and PAC upstream sequences often present in RNA polymerase subunit genes. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis mobility of the YKL1 gene product is equivalent to that of the RNA polymerase III subunit C25. Finally, a C25 conditional mutant grown at the nonpermissive temperature synthesizes tRNA at reduced rates relative to 5.8S rRNA, a hallmark of all characterized RNA polymerase III mutants.


1993 ◽  
Vol 120 (3) ◽  
pp. 613-624 ◽  
Author(s):  
P Hartl ◽  
J Gottesfeld ◽  
D J Forbes

A normal consequence of mitosis in eukaryotes is the repression of transcription. Using Xenopus egg extracts shifted to a mitotic state by the addition of purified cyclin, we have for the first time been able to reproduce a mitotic repression of transcription in vitro. Active RNA polymerase III transcription is observed in interphase extracts, but strongly repressed in extracts converted to mitosis. With the topoisomerase II inhibitor VM-26, we demonstrate that this mitotic repression of RNA polymerase III transcription does not require normal chromatin condensation. Similarly; in vitro mitotic repression of transcription does not require the presence of nucleosome structure or involve a general repressive chromatin-binding protein, as inhibition of chromatin formation with saturating amounts of non-specific DNA has no effect on repression. Instead, the mitotic repression of transcription appears to be due to phosphorylation of a component of the transcription machinery by a mitotic protein kinase, either cdc2 kinase and/or a kinase activated by it. Mitotic repression of RNA polymerase III transcription is observed both in complete mitotic cytosol and when a kinase-enriched mitotic fraction is added to a highly simplified 5S RNA transcription reaction. We present evidence that, upon depletion of cdc2 kinase, a secondary protein kinase activity remains and can mediate this in vitro mitotic repression of transcription.


Sign in / Sign up

Export Citation Format

Share Document