Xu Y, Zhu Q, Panbangred W, Shirasu K, Lamb C
Plant Biology Laboratory, The Salk Institute for Biological Studies, San Diego, CA, 92186, USA.
Plant Mol Biol. 1996 Feb;30(3):387-401. doi: 10.1007/BF00049319.
A new basic chitinase gene, designated RC24, was isolated from a rice genomic library. The predicted RC24 protein contains 322 amino acid residues and exhibits 68% to 95% amino acid identity with known class I rice chitinases. RC24 protein expressed in Escherichia coli exhibited chitinase activity and strongly inhibited bacterial growth. Two transcription start sites of the RC24 gene were mapped by primer extension analysis of both rice native RNA and in vitro transcribed RNA using a RC24 promoter/GUS (beta-glucuronidase) gene fusion as a template. The 5'-flanking region of RC24 contained several putative stress-responsive cis-acting elements. A basal level of RC24 transcripts was detected in rice root and stem tissues, but not in leaf tissues. RC24 transcripts rapidly accumulated within 1 h after fungal elicitor treatment of suspension-cultured cells, and the levels continued to increase for at least 9 h. RC24 transcript accumulation was also observed in intact leaf tissues upon wounding, Transgenic rice plants containing the RC24/GUS gene fusion further confirmed that the RC24 gene showed a tissue-specific expression pattern and that transcription of the RC24 propmoter was sensitively and rapidly activated by wounding.
从水稻基因组文库中分离出一个新的碱性几丁质酶基因，命名为RC24。预测的RC24蛋白含有322个氨基酸残基，与已知的I类水稻几丁质酶的氨基酸同一性为68%至95%。在大肠杆菌中表达的RC24蛋白表现出几丁质酶活性，并强烈抑制细菌生长。以RC24启动子/GUS（β-葡萄糖醛酸酶）基因融合体为模板，通过对水稻天然RNA和体外转录RNA进行引物延伸分析，确定了RC24基因的两个转录起始位点。RC24的5'侧翼区域包含几个假定的应激反应顺式作用元件。在水稻根和茎组织中检测到RC24转录本的基础水平，但在叶组织中未检测到。悬浮培养细胞经真菌激发子处理后1小时内，RC24转录本迅速积累，且其水平至少持续增加9小时。在受伤的完整叶组织中也观察到RC24转录本的积累。含有RC24/GUS基因融合体的转基因水稻植株进一步证实，RC24基因表现出组织特异性表达模式，且RC24启动子的转录受到伤口的敏感而快速激活。
