GORDITA (AGL63) is a young paralog of the Arabidopsis thaliana Bsister MADS box gene ABS (TT16) that has undergone neofunctionalization
GORDITA (AGL63) is a young paralog of the Arabidopsis thaliana Bsister MADS box gene ABS (TT16) that has undergone neofunctionalization
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DOI：
10.1111/j.1365-313x.2010.04290.x
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发表时间：
2010-09-01
期刊：
影响因子：
7.2
通讯作者：
Becker, Annette
中科院分区：
文献类型：
--
作者：
Erdmann, Robert;Gramzow, Lydia;Becker, Annette
mikc型MADS结构域蛋白是被子植物花发育的关键调控因子。B姐妹基因构成了一个与B类花同源基因关系密切的进化支，保存了3亿多年。拟南芥b姐妹基因ABS的功能丧失表型是轻微的：突变体表现出种子颜色降低和内皮细胞发育缺陷。本研究以拟南芥中与ABS亲缘关系最密切的同源基因GORDITA （GOA，原AGL63）为研究对象，该基因被认为与ABS有冗余作用。系统进化树分析表明，导致ABS和GOA的重复发生在十字花科植物多样化的过程中，进一步的分析表明GOA是在宽松的选择压力下进化的。GOA基因的敲低表型表明该基因在果实纵向生长中起作用，而GOA基因的过表达导致花结构紊乱，萼片增加心皮样特征。考虑到其他b姐妹基因的系统发育和功能，我们的数据表明，与ABS相比，GOA进化出了一种新的功能。蛋白质分析表明，GOA特异性的“异常”结构域是蛋白质二聚化所必需的，而其他mikc型蛋白则需要K结构域进行二聚化。此外，没有发现ABS和GOA的共同蛋白相互作用伙伴。我们的实验表明，蛋白质结构域的修饰和表达模式的改变可以在相对较短的时间内导致新的基因功能，并强调了基因复制后实现新功能化的分子机制。
MIKC-type MADS domain proteins are key regulators of flower development in angiosperms. B-sister genes constitute a clade with a close relationship to class B floral homeotic genes, and have been conserved for more than 300 million years. The loss-of-function phenotype of the A. thaliana B-sister gene ABS is mild: mutants show reduced seed coloration and defects in endothelium development. This study focuses on GORDITA (GOA, formerly known as AGL63), the most closely related paralog of ABS in A. thaliana, which is thought to act redundantly with ABS. Phylogenetic trees reveal that the duplication leading to ABS and GOA occurred during diversification of the Brassicaceae, and further analyses show that GOA has evolved under relaxed selection pressure. The knockdown phenotype of GOA suggests a role for this gene in fruit longitudinal growth, while over-expression of GOA results in disorganized floral structure and addition of carpel-like features to sepals. Given the phylogeny and function of other B-sister genes, our data suggest that GOA has evolved a new function as compared to ABS. Protein analysis reveals that the GOA-specific 'deviant' domain is required for protein dimerization, in contrast to other MIKC-type proteins that require the K domain for dimerization. Moreover, no shared protein interaction partners for ABS and GOA could be identified. Our experiments indicate that modification of a protein domain and a shift in expression pattern can lead to a novel gene function in a relatively short time, and highlight the molecular mechanism by which neofunctionalization following gene duplication can be achieved.