Discovery of a stage of formation in the cytoplasm for the TFIID transcription factor
The TAF2-TAF8-TAF10 complex forms in the cytoplasm before it enters into the nucleus of the cell and joins TFIID-precursor.
Jan. 14, 2015
The international team coordinated by Imre Berger (EMBL) and Làszlò Tora (IGBMC) just demonstrated that the TFIID transcription factor, which controls the gene transcription in eukaryote cells, starts to assemble in building blocks in the cytoplasm before penetrating into the nucleus.
These results - published January 14, 2015 in Nature Communications - open up a new way for research on gene regulation and defects during transcription.
The gene transcription in the nuclei of eukaryote cells involves a hundred of regulating proteins, which interact and allow the reading of the gene to begin "at the right place and at the right time". Within the nucleus, the TFIID multiprotein complex plays the central role of being a "platform of assembly" during the phase of initiation of the gene transcription by the RNA polymerase II.
The structure of the human TFIID and the subunits composing it (such as TBP - TATA Binding Protein - and several TBP Associated Factors - TAFs) are increasingly known. However, the way by which these subunits gather to form the TFIID "key molecule" was little explored until now. The international team composed of seven research groups in France (Làszlò Tora’s and Patrick Schultz’s teams in IGBMC and Imre Berger’s team in EMBL, Grenoble), Germany and the United Kingdom.
In this new study, various experimental exploratory techniques allowed to highlight a TFIID sub-complex made of TAF2, TAF8 and TAF10 proteins, which assemble in the cytoplasm, before entering the nucleus. By observing the interactions between these three TAFs, the study also revealed the central role of TAF8 in the initial formation of this cytoplasmic complex and underlined that the interactions between TAF2 and TAF8 are crucial for both its formation and its incorporation in the TFIID-precursor, in the nucleus. Furthermore, the 3D- structure of TAF8 with TAF10 was determined.
The pre-assembly of various TAFs in well-defined TFIID building blocks in the cytoplasm open up the way for new research prospects on the formation and function of the TFIID transcription factor. Moreover, applied to the various subunits of other multiprotein complexes, which are involved in the regulation of the genetic information, these new findings will certainly lead to a better understanding of the mechanisms of assembly of these multiprotein complexes, and potentially uncover reasons for their dysfunction during transcription in particular in human cells.