Arabidopsis thaliana T-DNA Mutants Implicate GAUT Genes in the Biosynthesis of Pectin and Xylan in Cell Walls and Seed Testa
Arabidopsis thaliana T-DNA Mutants Implicate GAUT Genes in the Biosynthesis of Pectin and Xylan in Cell Walls and Seed Testa
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DOI：
10.1093/mp/ssp062
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发表时间：
2009-09-01
期刊：
影响因子：
27.5
通讯作者：
Mohnen, Debra
中科院分区：
文献类型：
--
作者：
Caffall, Kerry H.;Pattathil, Sivakumar;Mohnen, Debra
半乳糖醛酸转移酶 1 (GAUT1) 是一种 α 1,4-D-半乳糖醛酸转移酶，可将半乳糖醛酸从尿苷 5'-二磷酸半乳糖醛酸转移到果胶多糖同型半乳糖醛酸上（Sterling 等，2006）。拟南芥 GAUT1 相关基因家族由 25 个成员组成，编码 15 个 GAUT 和 10 个 GAUT 样 (GATL) 蛋白，与 GAUT1 的氨基酸序列相似性分别为 56-84% 和 42-53%。先前对 AtGAUT 的系统发育分析表明三个进化枝：A 至 C。对拟南芥、杨树和水稻 GAUT 家族的比较系统发育分析将 GAUT 细分为七个进化枝：进化枝 A-1（GAUT 1 至 3）；进化枝 A-1（GAUT 1 至 3）； A-2（GAUT4）； A-3（GAUT 5 和 6）； A-4（GAUT7）； B-1（GAUT 8 和 9）； B-2（GAUT 10 和 11）；和进化枝 C（GAUT 12 至 15）。拟南芥 GAUT 的分布与杨树直系同源物相当，但 GAUT2 除外，杨树中不存在 GAUT2。然而，与拟南芥或杨树相比，水稻没有 GAUT 2 和 12 的直系同源物，并且具有 GAUT 1、4 和 7 的多个明显的直系同源物。 15 个拟南芥 GAUT 基因中的 13 个的 26 个纯合 T-DNA 插入突变体的细胞壁糖基残基组成显示，gaut 突变体 6、8、9、10、11、12、13 和 14 的特定组织中的细胞壁与野生型拟南芥细胞壁显着且可重复地不同。果胶和木聚糖多糖受到 GAUT 功能丧失的影响，不同 gaut 突变体壁的半乳糖醛酸、木糖、鼠李糖、半乳糖和阿拉伯糖组成的改变证明了这一点。在 gaut 突变体中观察到的壁糖基残基组成表型表明，果胶和/或木聚糖中至少有六种不同的生物合成连接受到这些 GAUT 基因损伤的影响。还提供证据支持 GAUT11 在种子粘液膨胀以及种子壁和粘液组成中的作用。
Galacturonosyltransferase 1 (GAUT1) is an alpha 1,4-D-galacturonosyltransferase that transfers galacturonic acid from uridine 5'-diphosphogalacturonic acid onto the pectic polysaccharide homogalacturonan (Sterling et al., 2006). The 25-member Arabidopsis thaliana GAUT1-related gene family encodes 15 GAUT and 10 GAUT-like (GATL) proteins with, respectively, 56-84 and 42-53% amino acid sequence similarity to GAUT1. Previous phylogenetic analyses of AtGAUTs indicated three clades: A through C. A comparative phylogenetic analysis of the Arabidopsis, poplar and rice GAUT families has sub-classified the GAUTs into seven clades: clade A-1 (GAUTs 1 to 3); A-2 (GAUT4); A-3 (GAUTs 5 and 6); A-4 (GAUT7); B-1 (GAUTs 8 and 9); B-2 (GAUTs 10 and 11); and clade C (GAUTs 12 to 15). The Arabidopsis GAUTs have a distribution comparable to the poplar orthologs, with the exception of GAUT2, which is absent in poplar. Rice, however, has no orthologs of GAUTs 2 and 12 and has multiple apparent orthologs of GAUTs 1, 4, and 7 compared with either Arabidopsis or poplar. The cell wall glycosyl residue compositions of 26 homozygous T-DNA insertion mutants for 13 of 15 Arabidopsis GAUT genes reveal significantly and reproducibly different cell walls in specific tissues of gaut mutants 6, 8, 9, 10, 11, 12, 13, and 14 from that of wild-type Arabidopsis walls. Pectin and xylan polysaccharides are affected by the loss of GAUT function, as demonstrated by the altered galacturonic acid, xylose, rhamnose, galactose, and arabinose composition of distinct gaut mutant walls. The wall glycosyl residue compositional phenotypes observed among the gaut mutants suggest that at least six different biosynthetic linkages in pectins and/or xylans are affected by the lesions in these GAUT genes. Evidence is also presented to support a role for GAUT11 in seed mucilage expansion and in seed wall and mucilage composition.