This entry includes the Saccharomyces cerevisiae (Baker's yeast) protein SPT2 which is a chromatin protein involved in transcriptional regulation [ (PUBMED:15563464) ].
These proteins shows conservation of several domains across numerous species, including having a cluster of positively charged amino acids. This cluster probably functions in the binding properties of the proteins [ (PUBMED:15563464) ]. Sin1p/Spt2p probably modulates the local chromatin structure by binding two strands of double-stranded DNA at their crossover point.
Sin1p/Spt2p has sequence similarity to HMG1 and serves as a negative transcriptional regulator of a small family of genes that are activated by the SWI/SNF chromatin-remodelling complex. It is also involved in maintaining the integrity of chromatin during transcription elongation. Sin1p/Spt2 is required for, and is directly involved in, the efficient recruitment of the mRNA cleavage/polyadenylation complex [ (PUBMED:16788068) ]. Spt2 is also involved in regulating levels of histone H3 over transcribed regions [ (PUBMED:16449659) ].
Family alignment:
There are 1333 SPT2 domains in 1333 proteins in SMART's nrdb database.
Click on the following links for more information.
Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing SPT2 domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with SPT2 domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing SPT2 domain in the selected taxonomic class.
Cellular role (predicted cellular role)
Cellular role: transcription Binding / catalysis: DNA binding
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
Functional domains of the yeast chromatin protein Sin1p/Spt2p can bind four-way junction and crossing DNA structures.
J Biol Chem. 2005; 280: 5169-77
Display abstract
Sin1p/Spt2p is a yeast chromatin protein that, when mutated or deleted, alters the transcription of a family of genes presumably by modulating local chromatin structure. In this study, we investigated the ability of different domains of this protein to bind four-way junction DNA (4WJDNA) since 4WJDNA can serve as a model for bent double helical DNA and for the crossed structure formed at the exit and entry of DNA to the nucleosomes. Sequence alignment of Sin1p/Spt2p homologues from 11 different yeast species showed conservation of several domains. We found that three domains of Sin1p/Spt2p fused to glutathione S-transferase can each bind independently in a structure-specific manner to 4WJDNA as measured in a gel mobility shift assay. A feature common to these domains is a cluster of positively charged amino acids. Modification of this cluster resulted in either abolishment of binding or a change in the binding properties. One of the domains tested clearly bound superhelical DNA, although it failed to induce bending in a circularization assay. Poly-l-lysine, which may be viewed as a cluster of positively charged amino acids, bound 4WJDNA as well. Phenotypic analysis showed that disruption of any of these domains resulted in suppression of a his4-912delta allele, indicating that each domain has functional significance. We propose that Sin1p/Spt2p is likely to modulate local chromatin structure by binding two strands of double-stranded DNA at their crossover point.
