Expression in Escherichia coli: purification and properties of the recombinant human general transcription factor rTFIIB.

The human class II transcription factor TFIIB (rTFIIB) was overexpressed in Escherichia coli using a T7 RNA polymerase expression system and further purified to apparent homogeneity. The purified rTFIIB is identical to the endogenous factor according to the following criteria: molecular weight, microsequencing and mass spectra studies, ability to recognize the stable preinitiation complex formed between TFIID and the adenovirus 2 major late TATA box as demonstrated by gel shift as well as by DNase I footprinting assays, and transcription activity.