Nikolskaya A N, Pitkin J W, Schaeffer H J, Ahn J H, Walton J D
Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
Biochim Biophys Acta. 1998 Nov 27;1425(3):632-6. doi: 10.1016/s0304-4165(98)00117-2.
Genomic and cDNA copies of EXG1, a gene encoding an exo-beta1, 3-glucanase from the plant pathogenic fungus Cochliobolus carbonum, were isolated. The gene contains two introns of 50 and 53 bp, and the mRNA has a 5'-untranslated region of 90 nt and a 3'-untranslated region of 159 nt. The deduced protein product, EXG1p, has a predicted signal peptide of 17 amino acids, but based on the known N-terminus of the mature protein is further processed to remove an additional 25 amino acids. The sequence of EXG1p is not closely related to any other known protein, but has a low similarity (29% overall amino acid identity) to BGN13.1, an endo-beta1,3-glucanase from the mycoparasitic fungus Trichoderma harzianum. EXG1p contains two imperfect copies of a 23-amino acid motif that is found in several other proteins that interact with polysaccharides, including plant and bacterial polygalacturonases, phage neck appendage protein, phage endoneuramidase, and bacterial mannuronan epimerase.
从植物致病真菌玉米小斑病菌（Cochliobolus carbonum）中分离出了EXG1基因的基因组拷贝和cDNA拷贝，该基因编码一种外切-β1,3-葡聚糖酶。该基因含有两个分别为50 bp和53 bp的内含子，其mRNA具有一个90 nt的5'非翻译区和一个159 nt的3'非翻译区。推导的蛋白质产物EXG1p具有一个预测的由17个氨基酸组成的信号肽，但根据成熟蛋白已知的N端，还会进一步加工去除另外25个氨基酸。EXG1p的序列与任何其他已知蛋白质的关系都不密切，但与来自木霉属真菌哈茨木霉（Trichoderma harzianum）的内切-β1,3-葡聚糖酶BGN13.1有较低的相似性（总体氨基酸同一性为29%）。EXG1p包含一个23个氨基酸基序的两个不完美拷贝，该基序存在于其他几种与多糖相互作用的蛋白质中，包括植物和细菌的多聚半乳糖醛酸酶、噬菌体颈部附属蛋白、噬菌体神经氨酸酶和细菌甘露糖醛酸表异构酶。
