Häger K P, Braun H, Czihal A, Müller B, Bäumlein H
Department of Plant Ecology and Systematics, University of Bayreuth, Germany.
J Mol Evol. 1995 Oct;41(4):457-66. doi: 10.1007/BF00160317.
Legumin-like seed storage proteins have been intensively studied in crop plants. However, little is known about the molecular evolution of these proteins and their genes and it was assumed that they originated from an ancestral gene that already existed at the beginning of angiosperm evolution. We have evidence for the ubiquitous occurrence of homologous proteins in gymnosperms as well. We have characterized the major seed storage globulin from Ginkgo biloba by amino acid sequencing, which reveals clear homology to legumin-like proteins from angiosperms. The Ginkgo legumin is encoded by a gene family; we describe two of its members. The promoter regions contain sequence motifs which are known to function as regulatory elements involved in seed-specific expression of angiosperm legumins, although the tissues concerned are different in gymnosperms and angiosperms. The Ginkgo legumin gene structure is divergent from that of angiosperms and suggests that the evolution of legumin genes implicated loss of introns. From our data and from functional approaches recently described it becomes obvious that the posttranslational processing site of legumin precursors is less conserved than hitherto assumed. Finally, we present a phylogenetic analysis of legumin encoding sequences and discuss their utility as molecular markers for the reconstruction of seed plant evolution.
豆科植物样种子贮藏蛋白已在农作物中得到深入研究。然而，对于这些蛋白质及其基因的分子进化知之甚少，人们认为它们起源于被子植物进化初期就已存在的一个祖先基因。我们也有证据表明裸子植物中也普遍存在同源蛋白。我们通过氨基酸测序对银杏的主要种子贮藏球蛋白进行了表征，结果显示它与被子植物的豆科植物样蛋白有明显的同源性。银杏豆球蛋白由一个基因家族编码；我们描述了其中的两个成员。启动子区域包含一些序列基序，这些基序已知在被子植物豆球蛋白的种子特异性表达中起调控元件的作用，尽管裸子植物和被子植物中相关组织有所不同。银杏豆球蛋白基因结构与被子植物不同，这表明豆球蛋白基因的进化涉及内含子的丢失。从我们的数据以及最近描述的功能研究方法来看，很明显豆球蛋白前体的翻译后加工位点比迄今所认为的保守性更低。最后，我们对豆球蛋白编码序列进行了系统发育分析，并讨论了它们作为分子标记在重建种子植物进化中的用途。
