Huang H, Tudor M, Weiss C A, Hu Y, Ma H
Cold Spring Harbor Laboratory, NY 11724, USA.
Plant Mol Biol. 1995 Jun;28(3):549-67. doi: 10.1007/BF00020401.
The Arabidopsis AGL3 gene was previously identified on the basis of sequence similarity to the floral homeotic gene AGAMOUS (AG), which encodes a protein with a conserved MADS domain that is also found in human and yeast transcription factors (SRF and MCM1, respectively). Analysis of newly isolated full-length cDNA clones as well as genomic clones indicates that AGL3 is indeed a MADS-box gene with a general intron-exon structure similar to other plant MADS-box genes. However, unlike the others, which are expressed specifically in flowers, AGL3 is expressed in all above-ground vegetative organs, as well as in flowers, but not in roots. Furthermore, since AGL3 is MADS-domain protein, it is likely that it is also a DNA-binding protein regulating transcription. To characterize AGL3 as a DNA-binding protein in vitro, we expressed the AGL3 protein in Escherichia coli, and characterized its DNA-binding properties. We show that AGL3 binds to sequences which resemble the target sequences of SRF and MCM1, and have determined the consensus sequence to which AGL3 binds using random oligonucleotides. These results suggest that AGL3 is a widely distributed DNA-binding protein, which may be involved the transcriptional regulation of genes in many cells.
拟南芥AGL3基因先前是根据与花同源异型基因AGAMOUS（AG）的序列相似性鉴定出来的，AG编码一种具有保守MADS结构域的蛋白质，该结构域也分别存在于人类和酵母转录因子（SRF和MCM1）中。对新分离的全长cDNA克隆以及基因组克隆的分析表明，AGL3确实是一个MADS盒基因，其一般内含子-外显子结构与其他植物MADS盒基因相似。然而，与其他在花中特异性表达的基因不同，AGL3在所有地上营养器官以及花中均有表达，但在根中不表达。此外，由于AGL3是一种MADS结构域蛋白，它很可能也是一种调节转录的DNA结合蛋白。为了在体外将AGL3鉴定为一种DNA结合蛋白，我们在大肠杆菌中表达了AGL3蛋白，并对其DNA结合特性进行了表征。我们发现AGL3与类似于SRF和MCM1靶序列的序列结合，并使用随机寡核苷酸确定了AGL3结合的共有序列。这些结果表明，AGL3是一种广泛分布的DNA结合蛋白，可能参与许多细胞中基因的转录调控。
