3h7h
From Proteopedia
Crystal structure of the human transcription elongation factor DSIF, hSpt4/hSpt5 (176-273)
Structural highlights
Function[SPT4H_HUMAN] component of the drb sensitivity-inducing factor complex (dsif complex), which regulates mrna processing and transcription elongation by rna polymerase ii dsif positively regulates mrna capping by stimulating the mrna guanylyltransferase activity of rngtt/cap1a dsif also acts cooperatively with the negative elongation factor complex (nelf complex) to enhance transcriptional pausing at sites proximal to the promoter transcriptional pausing may facilitate the assembly of an elongation competent rna polymerase ii complex dsif and nelf promote pausing by inhibition of the transcription elongation factor tfiis/s-ii tfiis/s-ii binds to rna polymerase ii at transcription pause sites and stimulates the weak intrinsic nuclease activity of the enzyme cleavage of blocked transcripts by rna polymerase ii promotes the resumption of transcription from the new 3' terminus and may allow repeated attempts at transcription through natural pause sites dsif can also positively regulate transcriptional elongation and is required for the efficient activation of transcriptional elongation by the hiv- 1 nuclear transcriptional activator, tat dsif acts to suppress transcriptional pausing in transcripts derived from the hiv-1 ltr and blocks premature release of hiv-1 transcripts at terminator sequences [SPT5H_HUMAN] Component of the DRB sensitivity-inducing factor complex (DSIF complex), which regulates mRNA processing and transcription elongation by RNA polymerase II. DSIF positively regulates mRNA capping by stimulating the mRNA guanylyltransferase activity of RNGTT/CAP1A. DSIF also acts cooperatively with the negative elongation factor complex (NELF complex) to enhance transcriptional pausing at sites proximal to the promoter. Transcriptional pausing may facilitate the assembly of an elongation competent RNA polymerase II complex. DSIF and NELF promote pausing by inhibition of the transcription elongation factor TFIIS/S-II. TFIIS/S-II binds to RNA polymerase II at transcription pause sites and stimulates the weak intrinsic nuclease activity of the enzyme. Cleavage of blocked transcripts by RNA polymerase II promotes the resumption of transcription from the new 3' terminus and may allow repeated attempts at transcription through natural pause sites. DSIF can also positively regulate transcriptional elongation and is required for the efficient activation of transcriptional elongation by the HIV-1 nuclear transcriptional activator, Tat. DSIF acts to suppress transcriptional pausing in transcripts derived from the HIV-1 LTR and blocks premature release of HIV-1 transcripts at terminator sequences.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe eukaryotic transcription elongation factor DSIF [DRB (5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole) sensitivity-inducing factor] is composed of two subunits, hSpt4 and hSpt5, which are homologous to the yeast factors Spt4 and Spt5. DSIF is involved in regulating the processivity of RNA polymerase II and plays an essential role in transcriptional activation of eukaryotes. At several eukaryotic promoters, DSIF, together with NELF (negative elongation factor), leads to promoter-proximal pausing of RNA polymerase II. In the present paper we describe the crystal structure of hSpt4 in complex with the dimerization region of hSpt5 (amino acids 176-273) at a resolution of 1.55 A (1 A=0.1 nm). The heterodimer shows high structural similarity to its homologue from Saccharomyces cerevisiae. Furthermore, hSpt5-NGN is structurally similar to the NTD (N-terminal domain) of the bacterial transcription factor NusG. A homologue for hSpt4 has not yet been found in bacteria. However, the archaeal transcription factor RpoE" appears to be distantly related. Although a comparison of the NusG-NTD of Escherichia coli with hSpt5 revealed a similarity of the three-dimensional structures, interaction of E. coli NusG-NTD with hSpt4 could not be observed by NMR titration experiments. A conserved glutamate residue, which was shown to be crucial for dimerization in yeast, is also involved in the human heterodimer, but is substituted for a glutamine residue in Escherichia coli NusG. However, exchanging the glutamine for glutamate proved not to be sufficient to induce hSpt4 binding. Crystal structure of the human transcription elongation factor DSIF hSpt4 subunit in complex with the hSpt5 dimerization interface.,Wenzel S, Martins BM, Rosch P, Wohrl BM Biochem J. 2009 Dec 23;425(2):373-80. PMID:19860741[20] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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