Martin C H, Mayeda C A, Meyerowitz E M
Division of Biology, California Institute of Technology, Pasadena 91125.
J Mol Biol. 1988 May 20;201(2):273-87. doi: 10.1016/0022-2836(88)90138-6.
A cluster of three glue genes is present at chromosomal site 68C in the Drosophila melanogaster genome. In this study, we have used a comparative approach to investigate both the regulation and the evolution of the largest of these three genes, Sgs-3. The homologous genes from two related Drosophila species (D. erecta and D. yakuba) have been introduced into the D. melanogaster genome by P-factor-mediated transformation. When the resulting transformant lines were assayed for expression of the introduced genes, near-normal patterns of expression were seen. This demonstrates that the cis-acting regulatory sequences of the introduced Sgs-3-homologous glue genes are capable of interacting effectively with the transcriptional machinery of D. melanogaster. We have also determined the sequences of the Sgs-3-homologous glue genes from D. simulans, D. erecta and D. yakuba. These sequences were compared and used in two ways. The first was to locate conserved sequence elements in regions known to be involved in regulation of the gene. Several such elements were found; they represent potential sites of cis-acting regulatory sequences. Second, we looked at the evolution of the glue gene protein-coding regions. A very rapidly evolving central region of the protein-coding sequences was found; this region contains a striking series of tandem repeats of a five amino acid residue sequence in all four species. Also a number of conserved aspects of the Sgs-3-homologous proteins were found; these features may be essential to their function as a glue.
在黑腹果蝇基因组的68C染色体位点上存在一组由三个黏液基因组成的基因簇。在本研究中，我们采用了一种比较方法来研究这三个基因中最大的基因Sgs-3的调控和进化。通过P因子介导的转化，将来自两个相关果蝇物种（直立果蝇和雅库布果蝇）的同源基因导入黑腹果蝇基因组。当对所得转化株系进行导入基因的表达检测时，观察到了接近正常的表达模式。这表明导入的Sgs-3同源黏液基因的顺式作用调控序列能够与黑腹果蝇的转录机制有效相互作用。我们还确定了拟果蝇、直立果蝇和雅库布果蝇中Sgs-3同源黏液基因的序列。对这些序列进行了比较并以两种方式使用。第一种方式是在已知参与该基因调控的区域定位保守序列元件。发现了几个这样的元件；它们代表了顺式作用调控序列的潜在位点。第二种方式是研究黏液基因蛋白质编码区的进化。发现了蛋白质编码序列中一个快速进化的中央区域；该区域在所有四个物种中都包含一系列引人注目的五个氨基酸残基序列的串联重复。还发现了Sgs-3同源蛋白的一些保守方面；这些特征可能对它们作为黏液的功能至关重要。
