scholarly journals Splicing Factors Associate with Hyperphosphorylated RNA Polymerase II in the Absence of Pre-mRNA

1997 ◽  
Vol 136 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Euikyung Kim ◽  
Lei Du ◽  
David B. Bregman ◽  
Stephen L. Warren

The carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) contains multiple tandem copies of the consensus heptapeptide, TyrSerProThrSerProSer. Concomitant with transcription initiation the CTD is phosphorylated. Elongating polymerase has a hyperphosphorylated CTD, but the role of this modification is poorly understood. A recent study revealed that some hyperphosphorylated polymerase molecules (Pol IIo) are nonchromosomal, and hence transcriptionally unengaged (Bregman, D.B., L. Du, S. van der Zee, S.L. Warren. 1995. J. Cell Biol. 129: 287–298). Pol IIo was concentrated in discrete splicing factor domains, suggesting a possible relationship between CTD phosphorylation and splicing factors, but no evidence beyond immunolocalization data was provided to support this idea. Here, we show that Pol IIo co-immunoprecipitates with members of two classes of splicing factors, the Sm snRNPs and non-snRNP SerArg (SR) family proteins. Significantly, Pol IIo's association with splicing factors is maintained in the absence of pre-mRNA, and the polymerase need not be transcriptionally engaged. We also provide definitive evidence that hyperphosphorylation of Pol II's CTD is poorly correlated with its transcriptional activity. Using monoclonal antibodies (mAbs) H5 and H14, which are shown here to recognize phosphoepitopes on Pol II's CTD, we have quantitated the level of Pol IIo at different stages of the cell cycle. The level of Pol IIo is similar in interphase and mitotic cells, which are transcriptionally active and inactive, respectively. Finally, complexes containing Pol IIo and splicing factors can be prepared from mitotic as well as interphase cells. The experiments reported here establish that hyperphosphorylation of the CTD is a good indicator of polymerase's association with snRNP and SR splicing factors, but not of its transcriptional activity. Most importantly, the present study suggests that splicing factors may associate with the polymerase via the hyperphosphorylated CTD.

1999 ◽  
Vol 77 (4) ◽  
pp. 367-374 ◽  
Author(s):  
Sébastien B Lavoie ◽  
Alexandra L Albert ◽  
Alain Thibodeau ◽  
Michel Vincent

The phosphorylation of the carboxy-terminal domain of the largest subunit of RNA polymerase II plays an important role in the regulation of transcriptional activity and is also implicated in pre-mRNA processing. Different stresses, such as a heat shock, induce a marked alteration in the phosphorylation of this domain. The expression of stress genes by RNA polymerase II, to the detriment of other genes, could be attributable to such modifications of the phosphorylation sites. Using two phosphodependent antibodies recognizing distinct hyperphosphorylated forms of RNA polymerase II largest subunit, we studied the phosphorylation state of the subunit in different species after heat shocks of varying intensities. One of these antibodies, CC-3, preferentially recognizes the carboxy-terminal domain of the largest subunit under normal conditions, but its reactivity is diminished during stress. In contrast, the other antibody used, MPM-2, demonstrated a strong reactivity after a heat shock in most species studied. Therefore, CC-3 and MPM-2 antibodies discriminate between phosphoisomers that may be functionally different. Our results further indicate that the pattern of phosphorylation of RNA polymerase II in most species varies in response to environmental stress.Key words: RNA polymerase II, heat shock, phosphorylation, CC-3, MPM-2.


1998 ◽  
Vol 63 (0) ◽  
pp. 301-310 ◽  
Author(s):  
S. MCCRACKEN ◽  
E. ROSONINA ◽  
N. FONG ◽  
M. SIKES ◽  
A. BEYER ◽  
...  

2021 ◽  
Author(s):  
Blase Matthew LeBlanc ◽  
Rosamaria Yvette Moreno ◽  
Edwin Escobar ◽  
Mukesh Kumar Venkat Ramani ◽  
Jennifer S Brodbelt ◽  
...  

RNA polymerase II (RNAP II) is one of the primary enzymes responsible for expressing protein-encoding genes and some small nuclear RNAs. The enigmatic carboxy-terminal domain (CTD) of RNAP II and...


RSC Advances ◽  
2015 ◽  
Vol 5 (98) ◽  
pp. 80434-80440 ◽  
Author(s):  
Saihui Zhang ◽  
Yantao Shi ◽  
Wei Wang ◽  
Zhi Yuan

Association between zinc(ii)-dipicolylamine appended beta-cyclodextrin and CTD (carboxy-terminal domain of RNA polymerase II) peptides with different phosphorylation patterns was studied by ITC and NMR.


1997 ◽  
Vol 136 (1) ◽  
pp. 5-18 ◽  
Author(s):  
Lei Du ◽  
Stephen L. Warren

In the preceding study we found that Sm snRNPs and SerArg (SR) family proteins co-immunoprecipitate with Pol II molecules containing a hyperphosphorylated CTD (Kim et al., 1997). The association between Pol IIo and splicing factors is maintained in the absence of pre-mRNA, and the polymerase need not be transcriptionally engaged (Kim et al., 1997). The latter findings led us to hypothesize that a phosphorylated form of the CTD interacts with pre-mRNA splicing components in vivo. To test this idea, a nested set of CTD-derived proteins was assayed for the ability to alter the nuclear distribution of splicing factors, and to interfere with splicing in vivo. Proteins containing heptapeptides 1-52 (CTD52), 1-32 (CTD32), 1-26 (CTD26), 1-13 (CTD13), 1-6 (CTD6), 1-3 (CTD3), or 1 (CTD1) were expressed in mammalian cells. The CTD-derived proteins become phosphorylated in vivo, and accumulate in the nucleus even though they lack a conventional nuclear localization signal. CTD52 induces a selective reorganization of splicing factors from discrete nuclear domains to the diffuse nucleoplasm, and significantly, it blocks the accumulation of spliced, but not unspliced, human β-globin transcripts. The extent of splicing factor disruption, and the degree of inhibition of splicing, are proportional to the number of heptapeptides added to the protein. The above results indicate a functional interaction between Pol II's CTD and pre-mRNA splicing.


1997 ◽  
Vol 11 (20) ◽  
pp. 2645-2657 ◽  
Author(s):  
T. P. Cujec ◽  
H. Okamoto ◽  
K. Fujinaga ◽  
J. Meyer ◽  
H. Chamberlin ◽  
...  

2006 ◽  
Vol 26 (8) ◽  
pp. 3135-3148 ◽  
Author(s):  
Hongfang Qiu ◽  
Cuihua Hu ◽  
Chi-Ming Wong ◽  
Alan G. Hinnebusch

ABSTRACT The Paf1 complex (Paf1C) interacts with RNA polymerase II (Pol II) and promotes histone methylation of transcribed coding sequences, but the mechanism of Paf1C recruitment is unknown. We show that Paf1C is not recruited directly by the activator Gcn4p but is dependent on preinitiation complex assembly and Ser5 carboxy-terminal domain phosphorylation for optimal association with ARG1 coding sequences. Importantly, Spt4p is required for Paf1C occupancy at ARG1 (and other genes) and for Paf1C association with Ser5-phosphorylated Pol II in cell extracts, whereas Spt4p-Pol II association is independent of Paf1C. Since spt4Δ does not reduce levels of Pol II at ARG1, Ser5 phosphorylation, or Paf1C expression, it appears that Spt4p (or its partner in DSIF, Spt5p) provides a platform on Pol II for recruiting Paf1C following Ser5 phosphorylation and promoter clearance. spt4Δ reduces trimethylation of Lys4 on histone H3, demonstrating a new role for yeast DSIF in promoting a Paf1C-dependent function in elongation.


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