Interact with Spt6 (IWS1) was first identified in yeast to be interacting with RNAPII elongation factor Spt6 and the interaction was confirmed by ChIP (Krogan et al., 2002). IWS1/SPN1 (Suppress postrecruitment functions gene number 1) is evolutionary conserved, belonging to Spt gene family and is involved in post recruitment functions of RNAPII mediated transcription process (Fischbeck et al., 2002). In humans, IWS1 plays a role in histone modification and mRNA export by recruiting HYPB/Setd2 histone trimethyltransferase and Spt6 mediated IWS1 and REF1/Aly export adaptor on RNAPII large subunit C-terminal domain (CTD) (Yoh et al., 2008). Brassinosteriods are steroid hormones that play an important role in plant growth, development and stress response. Arabidopsis IWS1 plays a role in Brassinosteriod (BR) induced gene expression by interacting with BES1 transcription factor. Target genes in BR signalling pathways are regulated by BES1 through binding of BRs to its BRI1 membrane localized receptor. AtIWS1 loss of function mutant showed reduction in BR response resulting in genome wide decrease in BR induced gene expression, plant dwarfism and hypersensitivity to transcription elongation inhibitor (Li et al., 2010).

Last updated June 2023 by Ankita Abnave 

References:

Krogan NJ, Kim M, Ahn SH, Zhong G, Kobor MS, Cagney G, Emili A, Shilatifard A, Buratowski S, Greenblatt JF. RNA polymerase II elongation factors of Saccharomyces cerevisiae: a targeted proteomics approach. Mol Cell Biol. 2002 Oct;22(20):6979-92. doi: 10.1128/MCB.22.20.6979-6992.2002. PMID: 12242279; PMCID: PMC139818.

Fischbeck JA, Kraemer SM, Stargell LA. SPN1, a conserved gene identified by suppression of a postrecruitment-defective yeast TATA-binding protein mutant. Genetics. 2002 Dec;162(4):1605-16. doi: 10.1093/genetics/162.4.1605. PMID: 12524336; PMCID: PMC1462358.

Yoh SM, Lucas JS, Jones KA. The Iws1:Spt6:CTD complex controls cotranscriptional mRNA biosynthesis and HYPB/Setd2-mediated histone H3K36 methylation. Genes Dev. 2008 Dec 15;22(24):3422-34. doi: 10.1101/gad.1720008. PMID: 19141475; PMCID: PMC2607075.

Li L, Ye H, Guo H, Yin Y. Arabidopsis IWS1 interacts with transcription factor BES1 and is involved in plant steroid hormone brassinosteroid regulated gene expression. Proc Natl Acad Sci U S A. 2010 Feb 23;107(8):3918-23. doi: 10.1073/pnas.0909198107. Epub 2010 Feb 5. PMID: 20139304; PMCID: PMC2840484.