Department of Biochemistry, Molecular and Cell Biology, Division of Biological Sciences, Cornell University, Ithaca, New York 14853.
Proc Natl Acad Sci U S A. 1981 Oct;78(10):6196-200. doi: 10.1073/pnas.78.10.6196.
Two kinds of RNA are synthesized at the 87C1 chromosomal locus of Drosophila melanogaster in response to heat shock. One of these codes for the major heat shock protein, hsp70; the other, alphabeta RNA, derives from tandemly repeated alphabeta units consisting of adjacent alpha and beta DNA elements and has no identified translation product. Another DNA element, gamma, flanks the 5' ends of some alphabeta units. Here we report the complete nucleotide sequence of the 617-base-pair alpha and the 733-base-pair gamma element as well as a portion of the longer beta element. Sequence comparisons between the gamma element and the two hsp70 genes at 87C1 reveal that the 406 base pairs of gamma immediately upstream from the 5' end of the alphabeta unit exhibit 97.5% homology with the sequences at and upstream from the 5' end of the hsp70 genes. A similar homology also exists between gamma and an hsp70 gene present at another heat shock locus, 87A7, which contains no alphabeta units. These results, in conjunction with previous observations, strongly suggest that the coordinate induction by heat shock of the hsp70 and alphabeta genes is a consequence of their homologous 5' flanking sequences. We propose that this extraordinary degree of sequence conservation stems from the recent transposition of alphabeta DNA to the 87C1 locus, an event that brought alphabeta sequences adjacent to, and under the regulation of, the hsp70 control element.
果蝇 87C1 染色体位置上的两种 RNA 可响应热激而合成。其中一种编码主要热激蛋白 hsp70；另一种 alphabeta RNA 来自串联重复的 alphabeta 单元，由相邻的 alpha 和 beta DNA 元件组成，没有鉴定出翻译产物。另一个 DNA 元件 gamma 则位于一些 alphabeta 单元的 5' 端侧翼。在此，我们报告了 617bp 的 alpha 和 733bp 的 gamma 元件以及更长的 beta 元件的一部分的完整核苷酸序列。gamma 元件与 87C1 上的两个 hsp70 基因之间的序列比较表明，alphabeta 单元 5' 端上游的 406bp gamma 与 hsp70 基因的 5' 端及其上游序列具有 97.5%的同源性。gamma 与另一个热激位点 87A7 上的 hsp70 基因之间也存在类似的同源性，该基因不包含 alphabeta 单元。这些结果与先前的观察结果一起强烈表明，hsp70 和 alphabeta 基因的协调诱导是它们同源 5' 侧翼序列的结果。我们提出，这种非同寻常的序列保守性源于 alphabeta DNA 最近转位到 87C1 位点，这一事件使 alphabeta 序列与 hsp70 调控元件相邻，并受其调控。
