THE CONSERVED CORE DOMAIN OF THE HUMAN TATA-BINDING PROTEIN IS SUFFICIENT TO ASSEMBLE THE MULTISUBUNIT RNA-POLYMERASE I-SPECIFIC TRANSCRIPTION FACTOR SL1
U. Rudloff et al., THE CONSERVED CORE DOMAIN OF THE HUMAN TATA-BINDING PROTEIN IS SUFFICIENT TO ASSEMBLE THE MULTISUBUNIT RNA-POLYMERASE I-SPECIFIC TRANSCRIPTION FACTOR SL1, Proceedings of the National Academy of Sciences of the United Statesof America, 91(17), 1994, pp. 8229-8233
The human ribosomal RNA polymerase (Pot) I promoter selectivity factor
SL1 is a complex consisting of the TATA binding protein (TBP) and thr
ee TBP-associated factors (TAFs). We have investigated which elements
of TBP are involved in the assembly of Pol I-specific TBP-TAF complexe
s by comparing SL1 isolated from two human cell lines, one expressing
epitope-tagged full-length TBP and another expressing a deletion of ne
arly the entire N-terminal domain (e Delta NTBP). We have immunopurifi
ed epitope-tagged full-length TBP- and e Delta NTBP-TAF complexes and
show that e Delta NTBP reconstitutes SL1 activity almost as well as fu
ll-length TBP. Moreover, e Delta NTBP is shown to be associated with a
ll three Pol I-specific TAFs, Thus, the core of TBP alone if sufficien
t for the correct assembly of the Pol I-specific TBP-TAF complex, and
the variable N-terminal region of human TBP is not required for transc
riptional activity. We also demonstrate by an in vitro protein-protein
interaction assay that TBP directly interacts with the smallest TAF,
TAF(1)48.