Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del I.P.N, México, D.F., México.
Can J Microbiol. 2010 Feb;56(2):168-77. doi: 10.1139/w09-123.
The lambdatI terminator is located approximately 280 bp beyond the lambdaint gene, and it has a typical structure of an intrinsic terminator. To identify sequences required for lambdatI transcription termination a set of deletion mutants were generated, either from the 5' or the 3' end onto the lambdatI region. The termination efficiency was determined by measuring galactokinase (galK) levels by Northern blot assays and by in vitro transcription termination. The importance of the uridines and the stability of the stem structure in the termination were demonstrated. The nontranscribed DNA beyond the 3' end also affects termination. Additionally, sequences upstream have a small effect on transcription termination. The in vivo RNA termination sites at lambdatI were determined by S1 mapping and were located at 8 different positions. Processing of transcripts from the 3' end confirmed the importance of the hairpin stem in protection against exonuclease.
lambdaTI 终止子位于 lambdaTI 基因后约 280bp 处,具有内在终止子的典型结构。为了鉴定 lambdaTI 转录终止所需的序列,从 5'或 3'端生成了一组缺失突变体进入 lambdaTI 区域。通过 Northern blot 分析和体外转录终止来测定终止效率。证明了终止过程中尿嘧啶的重要性和茎结构的稳定性。3'端以外的未转录 DNA 也会影响终止。此外,上游序列对转录终止有很小的影响。通过 S1 作图确定了 lambdaTI 处的体内 RNA 终止位点,位于 8 个不同的位置。从 3'端加工的转录本证实了发夹茎在防止核酸外切酶方面的重要性。