Spt4 Background Information
Spt4, a Saccharomyces Cerevisiae RNA polymerase II (RNAP II) elongation factor, belongs to the DSIF complex, which also includes Spt5 (1). The DSIF complex regulates transcription elongation by mediating interactions between RNAPII and nucleosomes (2). The DSIF complex also plays a positive role in transcription elongation in conjunction with the Paf1 and FACT complexes (3,4). In addition to elongation, Spt4 mediates transcription-coupled repair of UV-induced DNA damage (2,5). Full transcription of lacZ genes, long and GC-rich DNA sequences requires Spt4 (2,5). When DNA damage is persistent, the absence of Spt4 leads to a delayed loss of transcription, suggesting that Spt4 is directly involved in mediating transcription shutdown (6). The activity of Spt4 and 5 depends upon the length of the C-terminal domain (CTD) of RNAPII, the presence of certain phosphoreceptors within the CTD, and the function of at least three CTD kinases (4).
