BIO-ORANIC CHEMICAL REEARCH ON CELL SIGNALS IN BACTERIA

1.黄点霉酚酮（Stingmolone）是黄点霉（Stigmatella aurantiaca）细胞在饥饿和光照条件下分泌的子实体诱导因子。两个基因，RelA和csgA被认为是参与子实体的形成在另一个Mkococcus，其中任何低分子量的因素，如豆酚酮尚未知道。在这项研究中，我们从S.并利用这些基因制造了细菌突变体。在RelA基因缺失的突变体中，豆酚酮的生产能力丧失。添加柱头菌碱不能恢复其形成子实体的能力。因此，RelA基因可能参与了豆酚酮的生产和感受性需求。csgA基因促进豆酚酮的合成，该基因的mRNA受饥饿诱导而不受光照诱导.植物病原细菌与植物的互作。(1)由假单胞菌pv.丁香假单胞菌（P.syringe pv.）分离出该基因，并将其破坏。在突变菌的培养液中，未检测到毒素。将该突变体应用于抗病植物，可明显抑制病菌的生长，减轻病害症状。那么毒素应该参与了细菌的致病性。(2)燕麦假单胞菌鞭毛蛋白以种特异性方式参与诱导水稻过敏反应。将致病性和非致病性菌株的细菌基因在E.杆菌这两种表达蛋白对水稻培养细胞的HR诱导作用相似。因此，鞭毛的特异性不依赖于氨基酸序列的差异。

1. Fruiting body formation in Myxococcus, Stigmatellaaurantiaca.Stingmolone is a fruiting body inducing factor secreted from the cells of Stigmatella aurantiaca when the cells are starved and irradiated with light. Two genes, RelA and csgA are thought to be involved in fruiting body formation in another Mkococcus in which any low molecular weight factor like stigmolone has not been known. In this study, we isolated homologs to these genes from S. aurantiaca and made the bacterial mutants using these genes. In RelA disrupted mutant, the productivity of stigmolone was lost. The ability to form fruiting body could not be recovered by addition of stigmobne. So, RelA should be involved in requirement of receptability as well as productivity of stigmolone. The gene, csgA promoted the synthesis of stigmolone The Mrna of the gene was induced by starvation but not by light irradiation.2. Plant-pathogen interaction of phytopathogenic bacteria.(1) Phytotoxin produced by Pseudomonas syringae pv. syringae.The gene cluster for synthesis of Phytotoxin in P. syringe pv. syringae was isolated and the gene was disrupted. In the cultured medium of the mutant bacterium, the toxin was not detected. When the mutant was applied to a susceptive plant, the growth of the bacterium was inhibited and the disease symptom was much diminished. Then the toxin should be involved in the pathogenecity of the bacterium.(2) Flagellins of Pseudomonas avenaeFlagellin of P. avenae is involved in induction of the hypersensitive reaction (HR) to rice in strain species specific manner. The bacterial genes from pathogenic and non-pathogenic strains were expressed in E. coli. Both of the expressed proteins could similarly elicit HR to rice cultured cells. So it is concluded that the specificity of the flagelns does not depend on the difference of the amino acid sequences.