Characterization of a New Antifungal Chitin-Binding Peptide from Sugar Beet Leaves
Characterization of a New Antifungal Chitin-Binding Peptide from Sugar Beet Leaves
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DOI：
10.1104/pp.113.1.83
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发表时间：
1997-01
期刊：
影响因子：
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通讯作者：
K. Nielsen;John E. Nielsen;Susan Mampusti Madrid;J. Mikkelsen
中科院分区：
文献类型：
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作者：
K. Nielsen;John E. Nielsen;Susan Mampusti Madrid;J. Mikkelsen
甜菜（Beta vulgaris L.）叶片的细胞间洗液（IWF）含有许多蛋白质，对破坏性叶片病原菌甜菜Cercospora beticola （Sacc.）具有体外抗真菌活性。其中鉴定出一种有效的抗真菌肽IWF4。IWF4的30个氨基酸残基序列富含半胱氨酸(6)和甘氨酸(7)，具有高度碱性等电点。IWF4与几丁质结合蛋白（如I类和IV类几丁质酶）的几丁质结合域具有同源性。因此，IWF4对甲壳素有很强的亲和力。值得注意的是，它结合几丁质比几丁质结合几丁质酶更强。获得了全长IWF4 cDNA克隆，该克隆编码76个氨基酸的前原蛋白，其中n端含有21个残基的推定信号肽，随后是30个残基的IWF4成熟肽，以及25个残基的酸性c端延伸。IWF4 mRNA仅在植物的地上部分表达，在幼叶、成熟叶和幼花中均有组成性表达。在甜菜球茎侵染期间和2,6-二氯异烟酸处理后，均未检测到IWF4蛋白或mRNA的诱导表达。
The intercellular washing fluid (IWF) from leaves of sugar beet (Beta vulgaris L.) contains a number of proteins exhibiting in vitro antifungal activity against the devastating leaf pathogen Cercospora beticola (Sacc.). Among these, a potent antifungal peptide, designated IWF4, was identified. The 30-amino-acid residue sequence of IWF4 is rich in cysteines (6) and glycines (7) and has a highly basic isoelectric point. IWF4 shows homology to the chitin-binding (hevein) domain of chitin-binding proteins, e.g. class I and IV chitinases. Accordingly, IWF4 has a strong affinity to chitin. Notably, it binds chitin more strongly than the chitin-binding chitinases. A full-length IWF4 cDNA clone was obtained that codes for a preproprotein of 76 amino acids containing an N-terminal putative signal peptide of 21 residues, followed by the mature IWF4 peptide of 30 residues, and an acidic C-terminal extension of 25 residues. IWF4 mRNA is expressed in the aerial parts of the plant only, with a constitutive expression in young and mature leaves and in young flowers. No induced expression of IWF4 protein or mRNA was detected during infection with C. beticola or after treatment with 2,6-dichloroisonicotinic acid, a well-known inducer of resistance in plants.