A novel gene, CBP1, encoding a putative extracellular chitin-binding protein, may play an important role in the hydrophobic surface sensing of Magnaporthe grisea during appressorium differentiation
A novel gene, CBP1, encoding a putative extracellular chitin-binding protein, may play an important role in the hydrophobic surface sensing of Magnaporthe grisea during appressorium differentiation
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DOI：
10.1094/mpmi.2002.15.5.437
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发表时间：
2002-05-01
影响因子：
3.5
通讯作者：
Yamaguchi, I
中科院分区：
文献类型：
--
作者：
Kamakura, T;Yamaguchi, S;Yamaguchi, I
稻瘟病菌的分生孢子芽管分化出一种特殊的细胞，即附着胞，这是侵入寄主植物所必需的。附着胞的形成也观察到人工固体基质，如聚碳酸酯。在cDNA差减文库中发现了一个新的芽管特异性基因--几丁质结合蛋白（chitin-binding protein，CBP 1）。CBP 1编码一种推定的胞外蛋白（信号肽），其在与真菌几丁质脱乙酰酶同源的中心结构域的两端具有两个类似的几丁质结合结构域，并且具有富含Ser/Thr相关的胞外基质蛋白（如凝集素）的C-末端结构域。CBP 1中几丁质结合结构域的共有序列在真菌中从未报道过，并且与植物凝集素和植物几丁质酶I类和IV类中的几丁质结合基序相似。破坏CBP 1以鉴定其功能。CBP 1的突变体不能在人工表面正常分化附着胞，但能在植物叶片表面正常分化附着胞。由于无效突变体Cbp 1-仅在人工表面上表现出异常的附着胞分化，并且对化学诱导剂敏感，因此CBP 1似乎在识别固体表面上的物理因子中起重要作用。
The conidial germ tube of the rice blast fungus, Magnaporthe grisea, differentiates a specialized cell, an appressorium, required for penetration into the host plant. Formation of the appressorium is also observed on artificial solid substrata such as polycarbonate. A novel emerging germ tube-specific gene, CBP1 (chitin-binding protein), was found in a cDNA subtractive differential library. CBP1 coded for a putative extracellular protein (signal peptide) with two similar chitin-binding domains at both ends of a central domain with homology to fungal chitin deacetylases and with a C-terminus domain rich in Ser/Thr related extracellular matrix protein such as agglutinin. The consensus sequence of the chitin-binding domain found in CBP1 has never been reported in fungi and is similar to the chitin-binding motif in plant lectins and plant chitinases classes I and IV. CBP1 was disrupted in order to identify its function. Null mutants of CBP1 failed to differentiate appressoria normally on artificial surface but succeeded in normally differentiating appressoria on the plant leaf surface. Since the null mutant Cbp1- showed abnormal appressorium differentiation only on artificial surfaces and was sensitive to the chemical inducers, CBP1 seemed to play an important role in the recognition of physical factors on solid surfaces.