EXPRESSION OF FIMBRIAE IN A ACTINOMYCETEMCOMITANS

说明(改编自《调查员摘要》)：本提案涉及 放线杆菌表达菌毛的分子基础 伴生放线菌(AA)。据介绍，牙周病原体AA 当刚从口腔中分离出来时，会表现出菌毛。流苏状AA 在肉汤培养中附着，而非菌毛AA要少得多 追随者。这一行为导致许多调查人员推断，菌毛是 对再生障碍性贫血来说是一个重要的毒力因素。Aa的菌毛表达可能是 在牙周组织定植期间对该生物体很重要。 这项提案的长期目标是确定基因 菌毛基因的组织和确定其分子基础 对这种潜在的毒力因子的调节。具体目标1是分离出 并克隆了AA菌毛基因(S)。AA菌毛克隆将从 聚合酶链式反应和聚合酶链式反应构建融合菌UTP001基因组文库 免疫学探头。广泛构建的基因组文库 动员粘粒载体，将用于互补研究 由UTP001产生的无菌毛、抗利福平的AA菌株。 特异靶2是为了确定DNA序列和转录 AA菌毛基因的组织(S)。菌毛基因作图和 测序将通过DNA限制分析来完成，桑格 测序，并通过对菌毛RNA转录本的分析。菌毛RNA将 通过Northern分析、S1核酸酶和引物延伸作图进行研究 要确定转录组织，请找到转录组织 起始点和基因的启动子区域。具体目标3将定义 指导菌毛调控的环境生长条件 在AA株UTP001中表达，并确定其分子基础。 监管。环境生长条件对植物生长的调控作用 菌毛的表达将首先在表型水平上进行研究，然后在 分子水平。分子特征研究将尽快开始 AS的初始DNA序列和转录组织被确定。 人们认为，理解菌毛表达的分子基础 AA将使研究人员能够开发出更好的治疗方法来对抗这种情况 最易感人群中的病原体。

DESCRIPTION (Adapted from investigator's Abstract): This proposal addresses the molecular basis for fimbrial expression by Actinobacillus actinomycetemcomitans (Aa). It is stated that the periodontal pathogen Aa expresses fimbriae when freshly isolated from the oral cavity. Fimbriate Aa are adherent in broth culture, while non-fimbriated Aa are much less adherent. This behavior led many investigators to reason that fimbriae are an important virulence factor for Aa. Fimbrial expression by Aa may be important to that organism during colonization of the periodontal tissues. The long term objectives of this proposal are to determine the genetic organization of the fimbrial genes and to ascertain the molecular basis for regulation of this potential virulence factor. Specific Aim 1 is to isolate and clone the Aa fimbrial gene(s). Aa fimbrial clones will be selected from genomic libraries of DNA from fimbriated strain UTP001 using PCR and immunologic probes. A genomic library, constructed in a broad range mobilization cosmid vector, will be used in complementation studies with a non-fimbriated, rifampicin resistant, Aa strain generated from UTP001. Specific Aim 2 is designed to determine the DNA sequence and transcriptional organization of the Aa fimbrial gene(s). Fimbrial gene mapping and sequencing will be accomplished by DNA restriction analysis, Sanger sequencing, and by analysis of fimbrial RNA transcripts. Fimbrial RNA will be studied by Northern analysis, S1 nuclease, and primer extension mapping to determine the transcriptional organization, locate the transcriptional start site, and the promoter region of the gene. Specific Aim 3 will define the environmental growth conditions that direct regulation of fimbrial expression in Aa strain UTP001, and to determine the molecular basis for the regulation. The regulatory effects of environmental growth conditions on fimbrial expression will be studied first at the phenotypic level, then at the molecular level. Molecular characterization studies will begin as soon as initial DNA sequence and transcriptional organization are ascertained. It is felt that understanding the molecular basis for fimbrial expression by Aa will enable researchers to develop better therapies to combat this pathogen in the most susceptible patient populations.