Identification and characterization of virulence determi

总结：该项目的目的是鉴定和表征白喉棒状杆菌的毒力决定因素，以了解这种重要的病原体如何引起疾病。白喉毒素是C.白喉毒素是由铁调节的，并且很可能额外的毒力因子与毒素的毒力因子协同调节。 在感染期间获得铁的能力对于许多细菌病原体引起疾病是必不可少的。 本实验室的早期研究表明，在C.白喉 最近的研究集中在：1）了解hmuO基因调控的分子机制，2）在C. 3）白喉杆菌遗传工具的开发;白喉杆菌中的DtxR同源物，以更准确地定义各种遗传系统的功能和4）白喉杆菌中的DtxR同源物称为MntR的表征。 已显示来自hmuO启动子的转录处于双重调节下，其中表达由血红素源（诸如血红素或血红蛋白）正调节，并且由白喉毒素阻遏蛋白（DtxR）和铁负调节。 本实验室的研究表明，血红素依赖性激活的hmuO启动子发生通过两个组件的信号转导系统，需要chrA和chrS基因，分别编码一个响应调节和传感器激酶。ABC（ATP结合盒）型转运系统参与了C.白喉和HmuT脂蛋白蛋白被认为是细胞表面血红素受体。建立了一个针对两种C.白喉和C.溃疡。 从最近完成的C.白喉基因组mntR基因被克隆，并被证明是一个五基因操纵子，也编码一个假定的ABC-金属转运蛋白的末端基因。 mntR的产物显示通过Mn依赖性机制调节该操纵子的表达。

Summary: The purpose of this project is to identify and characterize virulence determinants in Corynebacterium diphtheriae in order to understand how this important pathogen causes disease. Expression of diphtheria toxin, the primary virulence determinant of C. diphtheriae, is regulated by iron, and it is likely that additional virulence factors are coordinately regulated with that of the toxin. The ability to acquire iron during an infection is essential for many bacterial pathogens to cause disease. It was shown in earlier studies from this laboratory that the hmuO gene is required for the utilization of iron from heme and hemoglobin in C. diphtheriae. Recent studies have focused on; 1) understanding the molecular mechanisms of hmuO gene regulation, 2) the characterization of factors involved the transport of heme in C. diphtheriae 3) the development of genetic tools in C. diphtheriae to more accurately define the function of various genetic systems and 4)the characterization of a DtxR homolog in C diphtheriae termed MntR. Transcription from the hmuO promoter has been shown to be under dual regulation in which expression is positively regulated by a heme source, such as heme or hemoglobin, and negatively regulated by the diphtheria toxin repressor protein (DtxR) and iron. Studies in this laboratory have shown that heme-dependent activation of the hmuO promoter occurs through a two component signal transduction system that requires the chrA and chrS genes, which encode a response regulator and sensor kinase, respectively. An ABC (ATP-binding cassette) type transport system is involved in the utilization of heme and hemoglobin as iron sources in C. diphtheriae and the HmuT lipoprotein protein is proposed to be the cell surface heme receptor. A system for constructing defined mutation was developed for both C. diphtheriae and C. ulcerans. A homolog of dtxR, mntR, was identified from the recently completed C. diphtheriae genome. The mntR gene was cloned and was shown to be the terminal gene in a five gene operon that also encoded a putative ABC-metal transporter. The product of mntR was shown to regulate expression of this operon by a Mn-dependent mechanism.