ELONGATION-FACTOR TFIIS CONTAINS 3 STRUCTURAL DOMAINS - SOLUTION STRUCTURE OF DOMAIN-II

Transcription elongation by RNA polymerase II is regulated by the gene ral elongation factor TFIIS, This factor stimulates RNA polymerase II to transcribe through regions of DNA that promote the formation of sta lled ternary complexes. Limited proteolytic digestion showed that yeas t TFIIS is composed of three structural domains, termed I, II, and III , The two C-terminal domains (II and III) are required for transcripti on activity, The structure of domain III has been solved previously by using NMR spectroscopy, Here, we report the NMR-derived structure of domain II: a three-helix bundle built around a hydrophobic core compos ed largely of three tyrosines protruding from one face of the C-termin al helix, The arrangement of known inactivating mutations of TFIIS sug gests that two surfaces of domain II are critical for transcription ac tivity.