Structural highlights
Function
SPT6_YEAST Plays a role in maintenance of chromatin structure during RNA polymerase II transcription elongation thereby repressing transcription initiation from cryptic promoters. Mediates the reassembly of nucleosomes onto the promoters of at least a selected set of genes during repression; the nucleosome reassembly is essential for transcriptional repression. Essential for viability.[1] [2] [3] [4]
Publication Abstract from PubMed
The conserved and essential eukaryotic protein Spt6 functions in transcription elongation, chromatin maintenance, and RNA processing. Spt6 has three characterized functions. It is a histone chaperone capable of reassembling nucleosomes, a central component of transcription elongation complexes, and is required for recruitment of RNA processing factors to elongating RNA polymerase II (RNAPII). Here, we report multiple crystal structures of the 168-kDa Spt6 protein from Saccharomyces cerevisiae that together represent essentially all of the ordered sequence. Our two structures of the approximately 900-residue core region reveal a series of putative nucleic acid and protein-protein interaction domains that fold into an elongated form that resembles the bacterial protein Tex. The similarity to a bacterial transcription factor suggests that the core domain performs nucleosome-independent activities, and as with Tex, we find that Spt6 binds DNA. Unlike Tex, however, the Spt6 S1 domain does not contribute to this activity. Crystal structures of the Spt6 C-terminal region reveal a tandem SH2 domain structure composed of two closely associated SH2 folds. One of these SH2 folds is cryptic, while the other shares striking structural similarity with metazoan SH2 domains and possesses structural features associated with the ability to bind phosphorylated substrates including phosphotyrosine. Binding studies with phosphopeptides that mimic the RNAPII C-terminal domain revealed affinities typical of other RNAPII C-terminal domain-binding proteins but did not indicate a specific interaction. Overall, these findings provide a structural foundation for understanding how Spt6 encodes several distinct functions within a single polypeptide chain.
Crystal structures of the S. cerevisiae Spt6 core and C-terminal tandem SH2 domain.,Close D, Johnson SJ, Sdano MA, McDonald SM, Robinson H, Formosa T, Hill CP J Mol Biol. 2011 May 13;408(4):697-713. Epub 2011 Mar 17. PMID:21419780[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Hartzog GA, Wada T, Handa H, Winston F. Evidence that Spt4, Spt5, and Spt6 control transcription elongation by RNA polymerase II in Saccharomyces cerevisiae. Genes Dev. 1998 Feb 1;12(3):357-69. PMID:9450930
- ↑ Kaplan CD, Laprade L, Winston F. Transcription elongation factors repress transcription initiation from cryptic sites. Science. 2003 Aug 22;301(5636):1096-9. PMID:12934008 doi:http://dx.doi.org/10.1126/science.1087374
- ↑ Kaplan CD, Holland MJ, Winston F. Interaction between transcription elongation factors and mRNA 3'-end formation at the Saccharomyces cerevisiae GAL10-GAL7 locus. J Biol Chem. 2005 Jan 14;280(2):913-22. Epub 2004 Nov 5. PMID:15531585 doi:http://dx.doi.org/10.1074/jbc.M411108200
- ↑ Adkins MW, Tyler JK. Transcriptional activators are dispensable for transcription in the absence of Spt6-mediated chromatin reassembly of promoter regions. Mol Cell. 2006 Feb 3;21(3):405-16. PMID:16455495 doi:http://dx.doi.org/S1097-2765(05)01852-6
- ↑ Close D, Johnson SJ, Sdano MA, McDonald SM, Robinson H, Formosa T, Hill CP. Crystal structures of the S. cerevisiae Spt6 core and C-terminal tandem SH2 domain. J Mol Biol. 2011 May 13;408(4):697-713. Epub 2011 Mar 17. PMID:21419780 doi:10.1016/j.jmb.2011.03.002
