Tfb6, a previously unidentified subunit of the general transcription factor TFIIH, facilitates dissociation of Ssl2 helicase after transcription initiation.

Murakami, Kenji; Gibbons, Brian J; Davis, Ralph E; Nagai, Shigeki; Liu, Xin; Robinson, Philip J J; Wu, Tinghe; Kaplan, Craig D et al. · Proc Natl Acad Sci U S A · 2012

basic_science · Level V

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Abstract

General transcription factor TFIIH, previously described as a 10-subunit complex, is essential for transcription and DNA repair. An eleventh subunit now identified, termed Tfb6, exhibits 45% sequence similarity to human nuclear mRNA export factor 5. Tfb6 dissociates from TFIIH as a heterodimer with the Ssl2 subunit, a DNA helicase that drives promoter melting for the initiation of transcription. Tfb6 does not, however, dissociate Ssl2 from TFIIH in the context of a fully assembled transcription preinitiation complex. Our findings suggest a dynamic state of Ssl2, allowing its engagement in multiple cellular processes.

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