Functions of and interactions between the A and B blocks in adenovirus type 2-specific VARNA1 gene.
Functions of and interactions between the A and B blocks in adenovirus type 2-specific VARNA1 gene.
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2 型腺病毒特异性 VARNA1 基因中 A 和 B 块的功能和相互作用。
DOI：
10.1073/pnas.83.5.1285
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发表时间：
1986
影响因子：
11.1
通讯作者：
J. Railey
中科院分区：
文献类型：
--
作者：
R. E. Cannon;G. Wu;J. Railey
VARNA1 基因的内部转录控制区 (ITCR) 由一个 33 碱基对 (bp) 嵌段序列和两个 12 bp 序列块组成，这些序列块在 RNA 聚合酶 III 转录的大多数基因中高度保守。为了定义两个块的功能并研究两个块之间的相互作用，我们构建了具有改变的块间序列或转录间距的突变体。转录效率和竞争强度的结果表明，嵌段间序列是可有可无的，A和B嵌段对于转录控制至关重要。嵌段序列的主要功能之一是保持两个基本嵌段之间密切相互作用的最佳间距。缩短或延长突变体中的嵌段间距超出该范围会大大降低这些突变基因的转录效率和竞争强度。为了进一步研究两个区块之间的相互作用如何导致启动，确定了突变体的 RNA 产物的起始位点和大小。当嵌段间距小于 105 bp 时，野生型起始位点由 A 嵌段通过蛋白质与 B 嵌段相互作用后决定。然而，当嵌段间距大于105 bp时，优先使用靠近B嵌段的几个新起始位点。这表明，当 B 块与 A 块的相互作用因较长的间距而减弱时，新的起始位点可能由 B 块决定。该基因中导致启动的二分结构域之间的相互作用机制不同于 tRNA 和 Alu 家族 RNA 基因中的相互作用机制。
The internal transcriptional control region (ITCR) of VARNA1 gene consists of a 33-base-pair (bp) interblock sequence and two 12-bp sequence blocks that are highly conserved in most of the genes transcribed by RNA polymerase III. To define the functions of and study the interactions between the two blocks, we have constructed mutants with altered interblock sequence or spacing for transcription. The results of transcription efficiencies and competing strengths indicated that the interblock sequence was dispensable and the A and B blocks were essential for transcription control. One of the major functions of the interblock sequence was to maintain an optimal spacing for an intimate interaction between the two essential blocks. Shortening or elongating the interblock spacing in the mutants beyond this range drastically decreased the transcription efficiencies and competing strengths of these mutated genes. To further study how the interaction between the two blocks leads to initiation, the start sites and sizes of RNA products of the mutants were determined. When the interblock spacing was less than 105 bp, the wild-type start site was dictated by the A block after an interaction with the B block through proteins. However, when the interblock spacing was longer than 105 bp, several new start sites located closer to the B block were preferentially used. This suggests that new start sites may be dictated by the B block when its interaction with the A block is weakened by longer spacing. The mechanisms of interaction between the bipartite domain in this gene leading to initiation are different from those in tRNAs and Alu-family RNA genes.