Sequence of Mature Phosphoglycerate Kinase from Spinach Chloroplasts
Sequence of Mature Phosphoglycerate Kinase from Spinach Chloroplasts
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DOI：
10.1104/pp.103.4.1449
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发表时间：
1993-12
期刊：
影响因子：
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通讯作者：
U. Bertsch;T. Schlicher;I. Schroder;J. Soll
中科院分区：
文献类型：
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作者：
U. Bertsch;T. Schlicher;I. Schroder;J. Soll
PGK以两种同种型存在于高等植物中，其中一种位于细胞溶质区室中，另一种位于叶绿体基质中（安德森和阿德瓦尼，1970）。叶绿体同工酶催化光合碳还原循环中的一个步骤，而胞质酶参与糖酵解和光合异生。迄今为止报道的来自高等植物的PGK的唯一cDNA序列是来自小麦的同工酶的cDNA序列（Longstaff等人，1989年）。在这里，我们报告的核苷酸序列的叶绿体异构体的PGK从菠菜（菠菜）。这是首次报道的双子叶植物PGK序列。在用抗菠菜核苷二磷酸激酶的抗体筛选过程中，从菠菜cDNA表达文库中分离出菠菜PGK的部分cDNA。使用该部分克隆作为探针，对同一文库进行第二次筛选，分离出9个PGK cDNA克隆并测序。在这些cDNA克隆之一上发现的最长开放阅读框编码在PGK的假定NH 2末端之前具有28个额外氨基酸残基的蛋白质。由于该开放阅读框起始于cDNA的5'末端，因此它可能是不完整的，并且28个NH 2末端氨基酸仅代表叶绿体转运肽的一部分。这一观点得到了NH 2-末端肽的组成的支持，其符合叶绿体转运肽的典型氨基酸组成（von Heijne et al.，1989年）。此外，该NHZ-末端肽显示出与来自小麦的PGK的叶绿体同种型的叶绿体转运肽的一些序列同源性。菠菜PGK的预测蛋白质序列显示出相当大的同源性，从小麦PGK isofonns，指向单子叶植物和双子叶植物之间的PGK序列的高度保守。在氨基酸水平上，成熟菠菜蛋白与小麦叶绿体酶的同源性为87%，而与小麦胞质异构体的同源性为85%。菠菜序列与小麦叶绿体PGK序列同源性较高，
PGKs are present in higher plants in two isoforms, one of which is located in the cytosolic compartment, and the other of which is localized in the stroma of chloroplasts (Anderson and Advani, 1970). The chloroplast isoenzyme catalyzes one step in the photosynthetic carbon reduction cycle, whereas the cytosolic enzyme takes part in glycolysis and gluconeogenesis. The only cDNA sequences of PGKs from higher plants reported so far are those of isoenzymes from wheat (Longstaff et al., 1989). Here we report the nucleotide sequence for the chloroplast isoform of PGK from spinach (Spinacia oleracea). This is the first PGK sequence reported from a dicotyledonous plant. A partial cDNA for spinach PGK was isolated from a spinach cDNA expression library during a screening with an antibody raised against spinach nucleoside diphosphate kinase. Using this partial clone as a probe for a second screening of the same library, nine clones of cDNAs for PGK were isolated and sequenced. The longest open reading frame found on one of these cDNA clones codes for a protein with 28 additional amino acid residues preceding the putative NH2 terminus of PGK. Since this open readmg frame starts at the 5’ end of the cDNA, it is probably incomplete and the 28 NH2-terminal amino acids represent only part of a chloroplast transit peptide. This notion is supported by the composition of the NH2-terminal peptide, which conforms with the typical amino acid composition of chloroplast transit peptides (von Heijne et al., 1989). Moreover, this NHZ-terminal peptide shows some sequence homology to the chloroplast transit peptide of the chloroplast isoform of PGK from wheat. The predicted protein sequence of the spinach PGK shows considerable homology to both PGK isofonns from wheat, pointing toward a high degree of conservation of PGK sequences between monocotyledonous and dicotyledonous plants. At the amino acid level, the identity between the mature spinach protein and the wheat chloroplast enzyme is 87%, whereas it is 85% if compared with the cytosolic isoform from wheat. The close homology between the spinach sequence and the chloroplast PGK from wheat, as well as the