SEX PHEROMONES AND CONJUGATION IN STREPTOCOCCI

拟议工作的主要目标是表征关键分子 粪链球菌性信息素相关的交配系统方面。 注意力将集中在性信息素的生产， 接受者和某些人对这种信息素的反应 含质粒的供体。 部分研究将利用 最近鉴定了转座子Tn 916和Tn 917。 更具体地说， 将：1）遗传分析pAD 1信息素响应，利用 Tn 917作为插入诱变剂，E.大肠杆菌-链球菌穿梭 载体”来克隆和遗传分析质粒的选定片段; 2)鉴定质粒编码（受控）蛋白和RNA种类， 在cAD 1信息素反应过程中诱导，并试图将 从遗传研究中揭示的pAD 1决定簇的蛋白质; 3）生成 不能分泌cPD 1的粪链球菌突变体，检查它们的 排泄其他信息素的能力，并作为一个接受者的行为，并使用 探索信息素前体肽的可能存在; 4） 被认为含有结构基因的DNA片段的克隆和测序 5）纯化和表征cAD 1和cPD 1，并尝试 将它们的氨基酸序列与克隆的基因组DNA碱基序列相关联; 6） 确定性信息素生产的性质是关闭后， 质粒获取，通过分析新发现的质粒编码的修饰 cAD 1和cPD 1的形式;和7）使用一组S.粪菌“应答者” 菌株，筛选培养物中的其他细菌物种的信息素 活动

The primary objective of the proposed work is to characterize key molecular aspects of sex pheromone-related mating systems in Streptococcus faecalis. Attention will be focussed on both the production of sex pheromones by recipients and the response to such pheromones by certain plasmid-containing donors. Parts of the study will make use of the recently characterized transposons Tn916 and Tn917. More specifically we will: 1) Genetically analyze the pAD1 pheromone response, making use of Tn917 as an insertional mutagen and an E. coli-streptococcus "shuttle vector" to clone and genetically analyze selected segments of the plasmid; 2) Identify plasmid-encoded (controlled) protein and RNA species that are induced during the cAD1 pheromone response and attempt to relate the proteins to pAD1 determinants revealed from genetic studies; 3) Generate mutants of Streptococcus faecalis that fail to excrete cPD1, examine their ability to excrete other pheromones and to behave as a recipient, and use them to explore the possible existence of pheromone precursor peptides; 4) Clone and sequence segments of DNA believed to contain the structural gene for sex pheromone; 5) Purify and characterize cAD1 and cPD1 and attempt to relate their amino acid sequences to cloned genomic DNA base sequences; 6) Determine the nature by which sex pheromone production is shut off after plasmid acquisition, by analyzing newly discovered plasmid encoded modified forms of cAD1 and cPD1; and 7) Using a panel of S. faecalis "responder" strains, screen culture filtrates of other bacterial species for pheromone activity.