Mutational analysis of the pullulanase-type debranching enzyme of maize indicates multiple functions in starch metabolism
Mutational analysis of the pullulanase-type debranching enzyme of maize indicates multiple functions in starch metabolism
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DOI：
10.1105/tpc.007575
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发表时间：
2003-03-01
期刊：
影响因子：
11.6
通讯作者：
Myers, AM
中科院分区：
文献类型：
--
作者：
Dinges, JR;Colleoni, C;Myers, AM
植物含有两种类型的 α(1 -->6) 葡聚糖水解酶（淀粉脱支酶 [DBE]）。尽管许多植物物种已知异淀粉酶型 DBE 的缺陷表明淀粉生物合成中的功能，但影响普鲁兰酶型 DBE 的突变尚未被描述。我们描述了普鲁兰酶型 DBE 基因的无效突变，即玉米 Zpu1 中的突变插入。 zpu1-204 突变的纯合植物在瞬时和储存淀粉降解方面受到损害。因此，支链淀粉酶型DBE的水解活性有助于淀粉分解代谢。发育中的zpu1-204胚乳积累了野生型中未发现的支链麦芽低聚糖，并且缺乏线性麦芽低聚糖，这表明支链淀粉酶型DBE在仁淀粉形成过程中的葡聚糖水解中起作用。此外，在异淀粉酶型 DBE 缺乏的背景下，zpu1-204 会导致籽粒中植物糖原的显着积累，这在野生型中是看不到的。因此，普鲁兰酶型 DBE 部分补偿了异淀粉酶型 DBE 的缺陷，表明其在淀粉合成和降解过程中发挥作用。
Plants contain two types of alpha(1 -->6) glucan hydrolase (starch-debranching enzyme [DBE]). Mutations that affect the pullulanase-type DBE have not been described, although defects in isoamylase-type DBE, known in many plant species, indicate a function in starch biosynthesis. We describe a null mutation of a pullulanase-type DBE gene, a Mutator insertion in maize Zpu1. Plants homozygous for the zpu1-204 mutation are impaired in transient and storage starch degradation. Thus, hydrolytic activity of pullulanase-type DBE contributes to starch catabolism. Developing zpu1-204 endosperm accumulates branched maltooligosaccharides not found in the wild type and is deficient in linear maltooligosaccharides, indicating that the pullulanase-type DBE functions in glucan hydrolysis during kernel starch formation. Furthermore, in a background deficient in isoamylase-type DBE, zpu1-204 conditions a significant accumulation of phytoglycogen in the kernel that is not seen in the wild type. Therefore, pullulanase-type DBE partially compensates for the defect in isoamylase-type DBE, suggesting a function during starch synthesis as well as degradation.