tokens: Mutation of a 20-base pair sequence of the gamma-gene 5'-untranslated region ( UTR ) led to derepression of beta-promoter activity .
folded_tokens: mutation of a 20-base pair sequence of the gamma-gene 5'-untranslated region ( utr ) led to derepression of beta-promoter activity .
labels: O O O O O O O O B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O B-DNA_domain_or_region O O O O O B-DNA_domain_or_region O O