Relationships between starch synthase I and branching enzyme isozymes determined using double mutant rice lines.
Relationships between starch synthase I and branching enzyme isozymes determined using double mutant rice lines.
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DOI：
10.1186/1471-2229-14-80
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发表时间：
2014-03-26
影响因子：
5.3
通讯作者：
Fujita N
中科院分区：
文献类型：
--
作者：
Abe N;Asai H;Yago H;Oitome NF;Itoh R;Crofts N;Nakamura Y;Fujita N
淀粉是植物贮藏组织中最重要的碳水化合物。淀粉生物合成中至少有四种酶的多种同工酶。这些同工酶中的一些被认为相互作用并形成有效淀粉生物合成的复合物。在这些酶类别中，淀粉酶（SS）和分支酶（BE）发挥特别重要的作用。为了探讨水稻胚乳发育过程中可溶性SS活性的主要组分BEI和BEIIb与可溶性SS活性的最大组分SSI之间的关系，我们构建了SS 1/be 1和SS 1 L /be 2b双突变系。ss 1/be 1的种子重量与野生型相当，但大多数ss 1/be 2b种子是不育的，没有获得双隐性植株。由渗漏ss 1突变体（ss 1 L）和be 2b衍生的双隐性突变系ss 1 L /be 2b的种子重量高于单一be 2b突变体。支链淀粉在ss 1/be 1胚乳中的链长分布的分析揭示了附加效应的SSI和BEI的支链淀粉结构。链长度分析表明，BEIIb缺陷显着降低支链淀粉的短链的比例ss 1 L /be 2b。ss 1/be 1和ss 1 L /be 2b胚乳淀粉中直链淀粉含量与野生型基本相同，而be 2b胚乳淀粉中直链淀粉含量高于野生型。SSI，BEI和BEIIb缺乏也影响了其他同工酶与淀粉粒的结合程度。双突变株系支链淀粉的链长分布分析表明，SSI和BEI或BEIIb主要独立发挥作用，分支BEIIb其次是SSI链延长。be 2b中直链淀粉含量的增加是因为支链淀粉生物合成减少;然而，在此背景下较低的SSI活性可能增强了支链淀粉生物合成，这是由于在单个突变体中发现的分支和伸长之间的不平衡的校正。SSI、BEI和BEIIb的缺失影响了其它淀粉合成同工酶对淀粉粒的亲和力，这一事实表明在水稻胚乳支链淀粉合成过程中SSI、BEI和BEIIb之间存在密切的相互作用。
Starch is the most important carbohydrate in plant storage tissues. Multiple isozymes in at least four enzyme classes are involved in starch biosynthesis. Some of these isozymes are thought to interact and form complexes for efficient starch biosynthesis. Of these enzyme classes, starch synthases (SSs) and branching enzymes (BEs) play particularly central roles. We generated double mutant lines (ss1/be1 and ss1 L /be2b) between SSI (the largest component of total soluble SS activity) and BEI or BEIIb (major BEs in developing rice endosperm) to explore the relationships among these isozymes. The seed weight of ss1/be1 was comparable to that of wild type, although most ss1/be2b seeds were sterile and no double recessive plants were obtained. The seed weight of the double recessive mutant line ss1 L /be2b, derived from the leaky ss1 mutant (ss1 L ) and be2b, was higher than that of the single be2b mutant. Analyses of the chain-length distribution of amylopectin in ss1/be1 endosperm revealed additive effects of SSI and BEI on amylopectin structure. Chain-length analysis indicated that the BEIIb deficiency significantly reduced the ratio of short chains in amylopectin of ss1 L /be2b. The amylose content of endosperm starch of ss1/be1 and ss1 L /be2b was almost the same as that of wild type, whereas the endosperm starch of be2b contained more amylose than did that of wild type. SSI, BEI, and BEIIb deficiency also affected the extent of binding of other isozymes to starch granules. Analysis of the chain-length distribution in amylopectin of the double mutant lines showed that SSI and BEI or BEIIb primarily function independently, and branching by BEIIb is followed by SSI chain elongation. The increased amylose content in be2b was because of reduced amylopectin biosynthesis; however, the lower SSI activity in this background may have enhanced amylopectin biosynthesis as a result of a correction of imbalance between the branching and elongation found in the single mutant. The fact that a deficiency of SSI, BEI, or BEIIb affected the affinity of other starch biosynthetic isozymes for the starch granule implies that there is a close interaction among SSI, BEI and BEIIb during amylopectin biosynthesis in rice endosperm.
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影响因子：
4.3
作者：
Hirose, T;Terao, T
通讯作者：
Terao, T
影响因子：
7.4
作者：
Fujita, N;Yoshida, M;Nakamura, Y
通讯作者：
Nakamura, Y
影响因子：
6.9
作者：
Fujita N;Toyosawa Y;Utsumi Y;Higuchi T;Hanashiro I;Ikegami A;Akuzawa S;Yoshida M;Mori A;Inomata K;Itoh R;Miyao A;Hirochika H;Satoh H;Nakamura Y
通讯作者：
Nakamura Y
影响因子：
4.3
作者：
Fujita, N;Kubo, A;Nakamura, Y
通讯作者：
Nakamura, Y
影响因子：
5.4
作者：
SANO, Y
通讯作者：
SANO, Y