Molecular Genetics and Biochemistry of a Streptomyces Extracellular Esterase

疥疮链霉菌是一种革兰氏阳性土壤细菌，是多种地下蔬菜疥疮病的致病微生物。这种病原体产生一种细胞外酯酶，这种酯酶可能与木质素的分解有关，木质素是一种蜡状聚酯化合物，覆盖在块茎表面，从而保护植物免受水分和可能的病原体入侵。该酯酶已被纯化并进行了表征。它的产生是由锌引起的，锌是木质素的一种成分。本研究的目的是阐明锌对这种诱导的作用机制。酯酶基因将被克隆并确定其序列。该基因的转录，酯酶mRNA的稳定性和翻译，以及酯酶的加工/分泌将被用于锌依赖性测试。病原体分泌这种酯酶也将被研究。本研究将为研究具有重要农业意义的病原菌疥疮链霉菌的基因表达和蛋白分泌机制提供重要的基础信息。研究结果将加深我们对基因调控机制和宿主-病原体相互作用分子生物学的认识。它们也可用于保护经济作物免受病原生物的感染。

Streptomyces scabies, a gram positive soil bacterium, is the causative organism for scab disease on a variety of underground vegetables. The pathogen produces an extracellular esterase which may be involved in the breakdown of suberin, a waxy polyester compound that covers the surface of the tuber and thus protect the plant against moisture and possibly pathogen invasion. This esterase has been purified and characterized. Its production is induced by zinc which was found to be a component of suberin. The goal of the research is to elucidate the mechanism by which zinc effects this induction. The esterase gene will be cloned and its sequence determined. Transcription of the gene, the stability and translation of the esterase mRNA, and processing/secretion of the esterase will be tested for zinc dependence. Secretion of this esterase by the pathogen will also be studied. This research will provide important basic information of the mechanisms of gene expression and protein secretion in Streptomyces scabies, an agriculturally important pathogen. The results will enhance our understanding of the mechanisms of gene regulation and the molecular biology of host-pathogen interactions. They may also be applied to the protection of economic crops against infection by pathogenic organisms.