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Regulation of RNA polymerase II processivity by Spt5 is restricted to a narrow window during elongation
Author(s) -
Fitz Johanna,
Neumann Tobias,
Pavri Rushad
Publication year - 2018
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.201797965
Subject(s) - processivity , elongation , elongation factor , rna polymerase ii , biology , polymerase , microbiology and biotechnology , transcription (linguistics) , gene , promoter , rna , gene expression , genetics , ribosome , materials science , metallurgy , ultimate tensile strength , linguistics , philosophy
Spt5 is a highly conserved RNA polymerase II (Pol II )‐associated pausing and elongation factor. However, its impact on global elongation and Pol II processivity in mammalian cells has not been clarified. Here, we show that depleting Spt5 in mouse embryonic fibroblasts ( MEF s) does not cause global elongation defects or decreased elongation rates. Instead, in Spt5‐depleted cells, a fraction of Pol II molecules are dislodged during elongation, thus decreasing the number of Pol II complexes that complete the transcription cycle. Most strikingly, this decrease is restricted to a narrow window between 15 and 20 kb from the promoter, a distance which coincides with the stage where accelerating Pol II attains maximum elongation speed. Consequently, long genes show a greater dependency on Spt5 for optimal elongation efficiency and overall gene expression than short genes. We propose that an important role of Spt5 in mammalian elongation is to promote the processivity of those Pol II complexes that are transitioning toward maximum elongation speed 15–20 kb from the promoter.