De Winter R F, Moss T
Cell. 1986 Jan 31;44(2):313-8. doi: 10.1016/0092-8674(86)90765-8.
The X. laevis ribosomal DNA spacer contains duplicated RNA polymerase I "spacer promoters" and an array of repeated 60/81 bp promoter-related sequences. The latter have been shown to enhance transcription from a 40S preribosomal RNA promoter in cis. Here we present evidence that at least one spacer promoter is also necessary for efficient enhancement. Deletion of the spacer promoter sequences in a construct carrying only one such promoter reduces 40S RNA transcription to approximately 10% of wild type. This effect apparently is caused by inactivation of the spacer promoter, since mutants in which 4-177 bp of the spacer promoter and adjacent sequences are deleted are functionally equivalent. Spacer promoters and 60/80 bp arrays therefore probably act together to enhance 40S pre-RNA transcription in X. laevis.
非洲爪蟾核糖体DNA间隔区包含重复的RNA聚合酶I“间隔区启动子”以及一系列重复的60/81 bp启动子相关序列。后者已被证明可顺式增强来自40S前核糖体RNA启动子的转录。在此我们提供证据表明，至少一个间隔区启动子对于有效增强也是必需的。在仅携带一个此类启动子的构建体中删除间隔区启动子序列会使40S RNA转录降低至野生型的约10%。这种效应显然是由间隔区启动子的失活引起的，因为间隔区启动子和相邻序列中4 - 177 bp被删除的突变体在功能上是等效的。因此，间隔区启动子和60/80 bp阵列可能共同作用以增强非洲爪蟾中40S前体RNA的转录。
