Håvik B, Ragnhildstveit E, Lorens J B, Saelemyr K, Fauske O, Knudsen L K, Fjose A
Department of Molecular Biology, University of Bergen, Bergen, N-5020, Norway.
Biochem Biophys Res Commun. 1999 Dec 20;266(2):532-41. doi: 10.1006/bbrc.1999.1854.
The paired domain (PD) is an evolutionarily conserved DNA-binding domain encoded by the Pax gene family of developmental regulators. The Pax proteins are transcription factors and are involved in a variety of processes such as brain development, patterning of the central nervous system (CNS), and B-cell development. In this report we demonstrate that the zebrafish Pax2 PD can interact with a novel type of DNA sequences in vitro, the triple-A motif, consisting of a heptameric nucleotide sequence G/CAAACA/TC with an invariant core of three adjacent adenosines. This recognition sequence was found to be conserved in known natural Pax5 repressor elements involved in controlling the expression of the p53 and J-chain genes. By identifying similar high affinity binding sites in potential target genes of the Pax2 protein, including the pax2 gene itself, we obtained further evidence that the triple-A sites are biologically significant. The putative natural target sites also provide a basis for defining an extended consensus recognition sequence. In addition, we observed in transformation assays a direct correlation between Pax2 repressor activity and the presence of triple-A sites. The results suggest that a transcriptional regulatory function of Pax proteins can be modulated by PD binding to different categories of target sequences.
配对结构域（PD）是一种由发育调节因子的Pax基因家族编码的进化保守的DNA结合结构域。Pax蛋白是转录因子，参与多种过程，如大脑发育、中枢神经系统（CNS）的模式形成和B细胞发育。在本报告中，我们证明斑马鱼Pax2 PD在体外可与一种新型DNA序列相互作用，即由七聚体核苷酸序列G/CAAACA/TC组成、具有三个相邻腺苷不变核心的三A基序。发现该识别序列在参与控制p53和J链基因表达的已知天然Pax5抑制元件中保守。通过在Pax2蛋白的潜在靶基因（包括pax2基因本身）中鉴定类似的高亲和力结合位点，我们获得了进一步的证据，表明三A位点具有生物学意义。推定的天然靶位点也为定义扩展的共有识别序列提供了基础。此外，我们在转化试验中观察到Pax2抑制活性与三A位点的存在之间存在直接相关性。结果表明，Pax蛋白的转录调节功能可通过PD与不同类别的靶序列结合来调节。
