Characterization and expression analysis of genes encoding phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxylase kinase of Lotus japonicus, a model legume.
Characterization and expression analysis of genes encoding phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxylase kinase of Lotus japonicus, a model legume.
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DOI：
10.1094/mpmi.2003.16.4.281
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发表时间：
2003-04
期刊：
影响因子：
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通讯作者：
T. Nakagawa;Tomoko Izumi;M. Banba;Y. Umehara;H. Kouchi;K. Izui;S. Hata
中科院分区：
文献类型：
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作者：
T. Nakagawa;Tomoko Izumi;M. Banba;Y. Umehara;H. Kouchi;K. Izui;S. Hata
磷酸烯醇式丙酮酸羧化酶（PEPCs）是豆科植物中一类在共生根瘤碳代谢中起重要作用的酶，它通过一种特异性蛋白激酶（PEPC-PK）对保守残基的磷酸化而被激活。我们的特点是两个PEPC异构体的百脉根，酰胺易位豆类，形成确定的结节的cDNA。一个基因编码结节增强型，这是更密切相关的PEPCs在酰胺型不确定的结节比那些在酰脲型确定的结节。另一个基因在地上部和根中表达水平较低。这两种形式都有假定的磷酸化位点Ser 11。我们还分离了L. - 是的在大肠杆菌中表达的重组PEPC-PK蛋白在体外可有效磷酸化重组玉米C4型PEPC。PEPC-PK在根瘤中的表达量较高，在地上部和根中的表达量也较高。原位杂交结果表明，PEPC和PEPC-PK的转录本在成熟根瘤中的表达模式相似，但在新出现的根瘤中的表达模式不同。当L.长时间黑暗和光照处理后，根瘤中PEPC-PK活性和PEPC、PEPC-PK的mRNA水平均降低，随后恢复，表明其受地上部光合产物转运量的调节。
Phosphoenolpyruvate carboxylases (PEPCs), one form of which in each legume species plays a central role in the carbon metabolism in symbiotic root nodules, are activated through phosphorylation of a conserved residue by a specific protein kinase (PEPC-PK). We characterized the cDNAs for two PEPC isoforms of Lotus japonicus, an amide-translocating legume that forms determinate nodules. One gene encodes a nodule-enhanced form, which is more closely related to the PEPCs in amide-type indeterminate nodules than those in ureide-type determinate nodules. The other gene is expressed in shoots and roots at a low level. Both forms have the putative phosphorylation site, Ser11. We also isolated a cDNA and the corresponding genomic DNA for PEPC-PK of L. japonicus. The recombinant PEPC-PK protein expressed in Escherichia coli phosphorylated recombinant maize C4-form PEPC efficiently in vitro. The level of mRNA for PEPC-PK was high in root nodules, and those in shoots and roots were also significant. In situ hybridization revealed that the expression patterns of the transcripts for PEPC and PEPC-PK were similar in mature root nodules, but were different in emerging nodules. When L. japonicus seedlings were subjected to prolonged darkness and subsequent illumination, the activity of PEPC-PK and the mRNA levels of both PEPC and PEPC-PK in nodules decreased and then recovered, suggesting that they are regulated according to the amounts of photosynthates transported from shoots.