Interactions of the mannose-binding rice lectin with sugar chains of ConA-binding glycoproteins secreted by rice blast fungus

水稻甘露糖结合凝集素（mannose-binding rice lectin，MRL）是由干旱、病害和创伤等逆境诱导产生的。MRL具有凝集稻瘟菌孢子和原生质体以及水稻黄单胞菌完整细胞的潜在活性，并在感染部位周围积累。MRL由一些同种凝集素组成; 2种主要的具有pi 4.85和4.74，次要的pi 4.66、4.56和4.44，而所有的作为单一肽具有约MW 15，000。我们已经分离并鉴定了对应于pI4.85的主要一个，命名为MRL 4.85。对MRL 4.85基因和基因组结构的分析表明：（1）MRL 4.85与水稻盐胁迫和干旱胁迫诱导的salT基因产物几乎完全相同;（2）MRL 4.85基因通过选择性剪接转录成至少5个mRNA，其中一个缺少8个氨基酸残基，没有火焰|调控MRL 4.85转录本的5 '-UTR长度不同，缺少MRL 4.85转录本所包含的部分序列。 关于我们 在一个盐基因中有ned。BAG文库的筛选和水稻基因组计划的数据表明，MRL 4.85基因位于水稻第一条染色体上，在MRL 4.85上游约130 kb处存在一个与同工凝集素类似的序列。我们尝试利用带有CaMV 35 S启动子的双元载体pC 1304 E，在其中整合了正链或负链，获得过量表达或抑制表达MRL 4.85产物的水稻转化体。在愈伤组织水平上获得了10多个转化子。通过Con A亲和层析和HPLC纯化了稻瘟菌，其可能与MRL相互作用，并具有促进植物中附着胞形成和感染菌丝生长的活性。主要的糖蛋白是MW 28 k，并且在许多AA残基处被糖链修饰，可证明不是通过N-糖基化而是通过O-糖基化。少

The mannose-binding rice lectin (MRL) is induced by some stresses of drought, disease and wound. MRL has a potential activity to agglutinate spores and protoplasts of Magnaporthe girisea and also intact cells of Xanthomonas oryzae, and also accumulated around the infection sites. MRL is composed of some isolectins ; 2 major ones have pi 4.85 and 4.74, the minor pi 4.66, 4.56, and 4.44, whereas all ones have about MW 15,000 as a single peptide. We have already isolated and identified the major one corresponding to pI4.85, named MRL4.85. Analysis of the MRL4.85 gene and the genome structures suggested that (1) MRL4.85 is almost identical to salt and drought stress-inducible salT gene products in rice plant, (2) MRL4 85 gene is transcribed to at least 5 mRNAs by alternative splicing ; one lacks 8 amino acid residues without flame | shift and the other differ in the length of 3'-UTR, (3) the 5'-UTR regulating the transcripts of MRL4.85 differs in length and lack the part of sequence contai … More ned in one of the salT gene. Further, screening of BAG library and the data of the rice genome project suggested that MRL4.85 gene is located at the first chromosome in rice plant and the similar sequence corresponding to an isolectin exists at about 130kb upstream of MRL4.85.To verify our hypotheses that MRL may function as plant antibodies or receptors in host-parasite interaction, we have tried to obtain the transformants of rice plant to express excessively or suppressively the MRL4.85 product, using the binary vector pC1304E with CaMV 35S promoter in which the positive or negative strands are integrated. And some ten transformants are obtained at callus level.Con A-binding glycoproteinis secreted from germinating conidia of M. grisea, which potentially interact with MRL and have activity to promote appressorium formation and growth of infection hyphae in planta, are purified by Con A affinity chromatography and HPLC. The major glycoprotein is MW 28k and modified by sugar chains at many AA residues, provably not by N-glycosylation but by O-glycosylation. Less