Roberton M, Chandler P M
Division of Plant Industry, CSIRO, Camberra, ACT, Austria.
Plant Mol Biol. 1992 Sep;19(6):1031-44. doi: 10.1007/BF00040534.
An antiserum raised against dehydrin from maize (Zea mays) recognised several polypeptides in extracts of pea (Pisum sativum) cotyledons. A cDNA expression library was prepared from mRNA of developing cotyledons, screened with the antiserum and positive clones were purified and characterised. The nucleotide sequence of one such clone, pPsB12, contained an open reading frame which would encode a polypeptide with regions of significant amino acid sequence similarity to dehydrins from other plant species. The deduced amino acid sequence of the pea dehydrin encoded by B12 is 197 amino acids in length, has a high glycine content (25.9%), lacks tryptophan and is highly hydrophilic. The polypeptide has an estimated molecular mass of 20.4 kDa and pI = 6.4. An in vitro synthesised product from the clone comigrates with one of the in vivo proteins recognised by the antiserum. A comparison of the pea dehydrin sequence with sequences from other species revealed conserved amino acid regions: an N-terminal DEYGNP and a lysine-rich block (KIKEKLPG), both of which are present in two copies. Unexpectedly, pea dehydrin lacks a stretch of serine residues which is conserved in other dehydrins. B12 mRNA and dehydrin proteins accumulated in dehydration-stressed seedlings, associated with elevated levels of endogenous abscisic acid (ABA). Applied ABA induced expression of dehydrins in unstressed seedlings. Dehydrin expression was rapidly reversed when seedlings were removed from the stress or from treatment with ABA and placed in water. During pea cotyledon development, dehydrin mRNA and proteins accumulated in mid to late embryogenesis. Dehydrin proteins were some of the most actively synthesised at about the time of maximum fresh weight and represent about 2% of protein in mature cotyledons.
一种针对玉米（Zea mays）脱水素产生的抗血清识别出豌豆（Pisum sativum）子叶提取物中的几种多肽。从发育中的子叶mRNA制备了一个cDNA表达文库，用该抗血清进行筛选，阳性克隆被纯化并鉴定。其中一个这样的克隆pPsB12的核苷酸序列包含一个开放阅读框，该开放阅读框将编码一种多肽，其氨基酸序列区域与其他植物物种的脱水素具有显著的相似性。由B12编码的豌豆脱水素的推导氨基酸序列长度为197个氨基酸，甘氨酸含量高（25.9%），缺乏色氨酸且高度亲水。该多肽的估计分子量为20.4 kDa，pI = 6.4。该克隆的体外合成产物与抗血清识别的一种体内蛋白质共迁移。将豌豆脱水素序列与其他物种的序列进行比较，发现了保守的氨基酸区域：一个N端的DEYGNP和一个富含赖氨酸的区域（KIKEKLPG），两者均以两个拷贝存在。出乎意料的是，豌豆脱水素缺乏一段在其他脱水素中保守的丝氨酸残基。B12 mRNA和脱水素蛋白在脱水胁迫的幼苗中积累，与内源性脱落酸（ABA）水平升高相关。施加ABA可诱导未受胁迫幼苗中脱水素的表达。当幼苗从胁迫或ABA处理中移出并置于水中时，脱水素的表达迅速逆转。在豌豆子叶发育过程中，脱水素mRNA和蛋白在胚胎发育中期至后期积累。脱水素蛋白在鲜重最大时是合成最活跃的蛋白之一，在成熟子叶中占蛋白质的约2%。
