The increment of SII-facilitated transcript cleavage varies dramatically between elongation competent and incompetent RNA polymerase II ternary complexes.

摘要: Abstract Elongation factor SII is required to increase the efficiency of transcription by RNA polymerase II through intrinsic arrest sites. ternary complexes exhibit a ribonuclease activity in presence SII, truncating nascent transcripts 3'-->5' direction. We show here that transcript cleavage an obligatory step re-establishing elongation competency have become blocked at site. SII-facilitated these arrested released 7-14 nucleotide fragments. In contrast, competent complexes, which are stalled because absence nucleoside triphosphate from reaction mixture, occurred primarily dinucleotide increments. can partially recreate phenotype and preference for large increment stalling such 3'-end contains consecutive U residues, mimics sequence 3'-ends complexes.