Site-directed mutagenesis of arginine 246, glutamic acid 247, and histidine 248 in the eukaryotic transcription factor S-II

When His²⁴⁸ of the transcription factor S-II was replaced by alanine or tyrosine, the activity of the resulting mutants was less than 30% of that of the wild-type S-II. When Arg²⁴⁶, Glu²⁴⁷, and His²⁴⁸ were all replaced by leucine, the resulting mutant showed complete loss of activity. These results indicate that the amino acid sequence Arg-Glu-His at positions 246-248 of S-II is important for its stimulatory activity. The mutant S-II with no activity could not form a complex with RNA polymerase II, unlike wild-type S-II, but retained ability to interact with DNA.