Lee S H, Lee M H, Chung W I, Liu J R
Department of Biological Science, Korea Advanced Institute of Science and Technology, Taejon.
Mol Gen Genet. 1998 Sep;259(5):516-22. doi: 10.1007/s004380050843.
A cDNA encoding a protein kinase, which may be involved in the wound signal transduction pathway, was isolated from Nicotiana tabacum. The cDNA, named WAPK, is 1227 bp in length and contains an ORF of 1017 bp. The ORF encodes a polypeptide of 339 amino acids, with a calculated molecular mass of 38234 Da. Analysis of the deduced amino acid sequence shows that the N-terminal region of WAPK contains a catalytic region composed of eleven subdomains which are typically found in Ser/Thr protein kinases. This region shows 78-84% sequence identity with similar regions of abscisic acid (ABA)-induced and external-stimuli-responsive protein kinases. However, the C-terminal region of WAPK shows little homology with similar regions of Ser/Thr protein kinases, except for a 16-amino acid stretch near the end of the catalytic domain. Kinase assays using a WAPK fusion protein expressed in E. coli revealed that WAPK autophosphorylates on serine residue(s). The WAPK gene is predominantly expressed in flowers, moderately in roots, and poorly in leaves. Transcripts were not detected in stems. The WAPK gene was induced by wounding (within 1.5 h), by abscisic acid (within 0.5 h), and by methyl jasmonate (within 2 h). The induction pattern of WAPK mRNA upon wounding was not affected by treatment with diethyldithiocarbamic acid, a reagent which inhibits jasmonic acid biosynthesis. These results suggest that the WAPK gene is regulated by ABA in the wound signal transduction pathway.
从烟草中分离出一个可能参与伤口信号转导途径的编码蛋白激酶的cDNA。该cDNA名为WAPK，长度为1227 bp，包含一个1017 bp的开放阅读框（ORF）。该ORF编码一个由339个氨基酸组成的多肽，计算分子量为38234 Da。对推导的氨基酸序列分析表明，WAPK的N端区域包含一个由11个亚结构域组成的催化区域，这些亚结构域通常存在于丝氨酸/苏氨酸蛋白激酶中。该区域与脱落酸（ABA）诱导的和外部刺激响应的蛋白激酶的相似区域具有78 - 84%的序列同一性。然而，WAPK的C端区域与丝氨酸/苏氨酸蛋白激酶的相似区域几乎没有同源性，除了催化结构域末端附近的一段16个氨基酸的序列。使用在大肠杆菌中表达的WAPK融合蛋白进行的激酶分析表明，WAPK在丝氨酸残基上进行自身磷酸化。WAPK基因主要在花中表达，在根中中度表达，在叶中表达较弱。在茎中未检测到转录本。WAPK基因在伤口处理后1.5小时内、脱落酸处理后0.5小时内以及茉莉酸甲酯处理后2小时内被诱导。用抑制茉莉酸生物合成的试剂二乙基二硫代氨基甲酸处理后，伤口诱导的WAPK mRNA的诱导模式不受影响。这些结果表明，在伤口信号转导途径中，WAPK基因受ABA调控。
