Department of Biology, McGill University, Montreal, QC H3A 1B1, Canada.
Mol Genet Genomics. 2012 Feb;287(2):143-53. doi: 10.1007/s00438-011-0667-3. Epub 2011 Dec 21.
Auxin plays crucial roles in plant development. Auxin-binding protein 1 (ABP1) is an auxin receptor required to coordinate cell division and expansion during postembryonic shoot development, and differential auxin responses during root growth. While ABP1 is encoded by a single gene in maize, multiple gene copies exist in teosinte, the wild relatives of maize. We have previously shown that some of the differences between these genes are caused by multiple transposon insertions in the promoter. Here we show that the different ABP1 promoter types confer differential gene expression levels on a firefly luciferase reporter gene. We also discovered a negative regulatory sequence upstream of the conserved transcriptional start site. When this sequence is insulated by an Ac-like transposon or deleted in natural ABP1 gene variants, expression levels are enhanced. Promoters combining both a MITE and a solo-LTR showed small but significant increase in expression compared to those containing only one insertion. This increase seems to be additive, suggesting that it may be due to enhancer sequences present within these transposons. Our results point to a potential role of the ABP1-associated transposons in the modulation of ABP1 gene expression.
生长素在植物发育中起着至关重要的作用。生长素结合蛋白 1（ABP1）是一种生长素受体，对于协调胚胎后芽发育过程中的细胞分裂和扩张，以及根生长过程中的差异生长素反应是必需的。虽然 ABP1 在玉米中由单个基因编码，但在玉米的野生近缘种大刍草中存在多个基因拷贝。我们之前已经表明，这些基因之间的一些差异是由于启动子中的多个转座子插入引起的。在这里，我们表明不同的 ABP1 启动子类型在萤火虫荧光素酶报告基因上赋予不同的基因表达水平。我们还发现了保守转录起始位点上游的一个负调控序列。当这个序列被 Ac 样转座子隔离或在天然 ABP1 基因变异体中缺失时，表达水平会增强。与仅含有一个插入的启动子相比，同时含有 MITE 和 solo-LTR 的启动子的表达水平略有但显著增加。这种增加似乎是累加的，表明这可能是由于这些转座子中存在增强子序列。我们的研究结果表明，ABP1 相关转座子在调节 ABP1 基因表达方面可能具有潜在作用。
