Lo K, Smale S T
Howard Hughes Medical Institute, University of California, Los Angeles, School of Medicine 90095-1662, USA.
Gene. 1996 Dec 5;182(1-2):13-22. doi: 10.1016/s0378-1119(96)00438-6.
Transcriptional initiator (Inr) elements, like TATA boxes, are found in the core promoters of many eukaryotic protein-coding genes. To facilitate the dissection of transcription initiation mechanisms, and to identify Inr elements within known and newly-discovered genes, the precise DNA sequence requirements for Inr activity must be defined. Previously, we reported a preliminary Inr consensus sequence based on an extensive mutant analysis carried out in HeLa cell extracts. This analysis was limited, however, because it was performed only with an in vitro transcription assay and with the mutants in only one promoter context. In this study, we have assessed the general validity of the functional Inr consensus sequence by analyzing a selected set of mutants in additional promoter contexts and with both in vivo and in vitro assays. In addition, we analyzed the evolutionary conservation of the Inr consensus sequence by determining the sequence requirements for Inr function in Drosophila embryo extracts. The results demonstrate the generality and strict conservation among vertebrates and invertebrates of the Inr consensus sequence, Py Py A+1 N T/A Py Py.
转录起始元件（Inr），与TATA框类似，存在于许多真核生物蛋白质编码基因的核心启动子中。为了便于剖析转录起始机制，并在已知和新发现的基因中鉴定Inr元件，必须明确Inr活性所需的精确DNA序列要求。此前，我们基于在HeLa细胞提取物中进行的广泛突变分析报道了一个初步的Inr共有序列。然而，该分析存在局限性，因为它仅通过体外转录测定进行，且仅在一种启动子背景下分析突变体。在本研究中，我们通过在其他启动子背景下分析一组选定的突变体，并结合体内和体外测定，评估了功能性Inr共有序列的普遍有效性。此外，我们通过确定果蝇胚胎提取物中Inr功能的序列要求，分析了Inr共有序列的进化保守性。结果表明，Inr共有序列Py Py A +1 N T/A Py Py在脊椎动物和无脊椎动物中具有普遍性和严格的保守性。
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