Sakakibara K, Nishiyama T, Kato M, Hasebe M
National Institute for Basic Biology, Okazaki, Japan.
Mol Biol Evol. 2001 Apr;18(4):491-502. doi: 10.1093/oxfordjournals.molbev.a003828.
Homeobox genes encode transcription factors involved in many aspects of developmental processes. The homeodomain-leucine zipper (HD-Zip) genes, which are characterized by the presence of both a homeodomain and a leucine zipper motif, form a clade within the homeobox superfamily and were previously reported only from vascular plants. Here we report the isolation of 10 HD-Zip genes (named PPHB:1-PPHB:10) from the moss Physcomitrella patens. Based on a phylogenetic analysis of the 10 PPHB: genes and previously reported vascular plant HD-Zip genes, all of the PPHB: genes except Pphb3 belong to three of the four HD-Zip subfamilies (HD-Zip I, II, and III), indicating that these subfamilies originated before the divergence of the vascular plant and moss lineages. Pphb3 is sister to the HD-Zip II subfamily and has some distinctive characteristics, including the difference of the a(1) and d(1) sites of its leucine zipper motif, which are well conserved in each HD-Zip subfamily. Comparison of the genetic divergence of representative HD-Zip I and II genes showed that the evolutionary rate of HD-Zip I genes was faster than that of HD-Zip II genes.
同源异型框基因编码参与发育过程多个方面的转录因子。同源异型域-亮氨酸拉链（HD-Zip）基因，其特征在于同时存在同源异型域和亮氨酸拉链基序，在同源异型框超家族中形成一个进化枝，此前仅在维管植物中报道过。在此，我们报道了从苔藓小立碗藓中分离出10个HD-Zip基因（命名为PPHB:1 - PPHB:10）。基于对这10个PPHB:基因与先前报道的维管植物HD-Zip基因的系统发育分析，除Pphb3外的所有PPHB:基因都属于四个HD-Zip亚家族中的三个（HD-Zip I、II和III），这表明这些亚家族在维管植物和苔藓谱系分化之前就已起源。Pphb3是HD-Zip II亚家族的姐妹基因，具有一些独特特征，包括其亮氨酸拉链基序的a(1)和d(1)位点的差异，这些位点在每个HD-Zip亚家族中都高度保守。对代表性HD-Zip I和II基因的遗传分化比较表明，HD-Zip I基因的进化速率比HD-Zip II基因快。
