Phosphorylation of the N‐terminal domain of Xenopus TATA‐box binding protein by DNA‐dependent protein kinase depends on the C‐terminal core domain

Abstract

DNA-dependent protein kinase (DNA-PK) has been shown to phosphorylate several transcription factors in vitro, suggesting that this nuclear enzyme -in addition to its role in DNA repair and recombination -may be involved in transcriptional regulation. In the typical mechanism the DNA-bound kinase phosphorylates a substrate that is bound to the same DNA molecule. Here I report that the Xenopus TATA-box binding protein (xTBP) is hyperphosphorylated by DNA-PK in vitro. The phosphorylation is in the N-terminal domain of the protein but depends fully on the presence of the C-terminal core domain.

Phosphorylation of Human General Transcription Factors TATA‐Binding Protein and Transcription Factor IIB by DNA‐Dependent Protein Kinase

“…By contrast, an undetectable amount of human TBP, or only a small fraction of Xenopus TBP, was hyperphosphorylated by DNA-PK (Fig. 1) [38]. Thus, the phosphorylation of TBP by DNA-PK may not contribute to the in vivo hyperphosphorylated forms of TBP.…”

“…On the other hand, in vitro and in vivo phosphorylation of TBP has been previously reported although its functional consequence has not been investigated. Human TBP can be phosphorylated in vitro by a kinase activity associated with TFIIH [37] and, more recently, Xenopus TBP has been shown to be phosphorylated in vitro by DNA-PK [38]. Consistent with our present results, DNA-PK phosphorylates Xenopus TBP in its N-terminal region but this depends on its C-terminal core domain, contrary to our results showing that the N-terminal region of human TBP (N160) alone is phosphorylated by DNA-PK (Fig.…”

“…Although it has not been clarified which component(s) of TIF-IB/Ribl DNA-PK phosphorylates in those systems, TBP could be a candidate target. Indeed, DNA-PK phosphorylates Xenopus TBP in vitro [38]. If the phosphorylation of TBP is responsible for the repression of Pol-I transcription, the apparently opposite effects of DNA-PK on Pol-I and Pol-I1 transcription could be attributed to different factors interacting with TBP in Pol-I and Pol-I1 transcription systems, including Pol Iand Pol 11-specific TBP-associated factors, TFIIB, and Pol-I1 Cterminal domain.…”

The TATA-box binding protein of Entamoeba histolytica: cloning of the gene and location of the protein by immunofluorescence and confocal microscopy

“…One of the challenges in the study of human parasites is to find differences between host and parasite molecules that can be used as drug targets, and to design vaccine targets. Differences in the TBP N-terminal domains could be useful to identify E. histolytica-specific transcription factors or other molecules involved in gene-expression regulation, like the DNA-dependent protein kinase that hyperphosphorylates the N-terminal domain of Xenopus TBP (Labhart, 1996). This phosphorylation was seen to be fully dependent on the presence of the Cterminal core domain.…”

“…E. histolytica has an A+T rich genome (67 mol%) (Sanchez et al, 1994;Tannich & Horstmann, 1992) and its codon usage is unusual, with 85 O/ O A + U in the third codon position (Bruchhaus et al, 1993). Putative TATA boxes with TATTAAA, TATAAA (Sanchez et al, 1994) and TATTTAAA sequences (Bruchhaus et al, 1993;Li et al, 1992) have been located 27 to 50 bp upstream from the ATG start codon. The ATTCA and ATCA sequences have been described as consensus transcription start sites (Bruchhaus et al, 1993).…”