Analysis of MGA protein from the Streptococcus pyogenes

描述（由申请人提供）：A组链球菌（链球菌 化脓性链球菌，GAS）是一种具有巨大医学重要性的细菌病原体， 人类，引起各种疾病综合征，其严重程度从 轻微到危及生命Mga是GAS的DNA结合蛋白，其激活 几个关键毒力基因的转录响应变化 环境条件，可能通过与其他监管机构的相互作用 细胞中的成分。Mga调节子编码的产物对于 GAS在宿主中的存活，包括抗吞噬M蛋白、M样 免疫球蛋白结合蛋白，分泌的补体抑制剂， 胶原样蛋白和C5 a肽酶。因此，Mga提供了一个优秀的 研究GAS发病机制中涉及的全球调控网络的模型系统 以及它们如何相互作用。然而，我们目前对Mga知之甚少， 包括蛋白质的哪些结构域对其功能至关重要， 环境信号控制Mga调节子。具体目标是 主要研究内容如下：（1）鉴定Mga与DNA结合的结构域， 表征它们在靶向特异性启动子中的作用;（2）确定它们在靶向特异性启动子中的作用。 共有Mga结合元件的每个已知的启动子位点， 鉴定特异性Mga/核苷酸相互作用;（3）研究 Mga的结构域是否直接与其他细菌组分相互作用， 干扰环境信号（即，Mga是双分量响应吗 regulator？）; (4)确定环境所需的其他因素 Mga调节子的调节，并评估其在全球毒力中的作用 调控这个建议的一个吸引人的特点是我们能够研究Mga 作为体外纯化蛋白和其GAS中的天然分子， 背景因此，我们将能够彻底解决GAS的关键问题 发病机制密切相关的环境调节的Mga 调节子本建议的总体目标是：（A）开展一项 Mga的结构/功能分析，并确定其机制， 关键GAS毒力调节因子促成链球菌疾病，和（B） 提高我们对调控途径的总体理解， 这些革兰氏阳性病原体的毒力。

DESCRIPTION (provided by applicant): The group A streptococcus (Streptococcus pyogenes, GAS) is a bacterial pathogen of enormous medical importance to humans, causing a variety of disease syndromes that range in severity from minor to life-threatening. Mga is a DNA-binding protein of GAS that activates the transcription of several key virulence genes in response to changing environmental conditions, likely through interactions with other regulatory components in the cell. The Mga regulon encodes products essential for the survival of GAS in the host, including the antiphagocytic M protein, M-like immunoglobulin binding proteins, the secreted inhibitor of complement, a collagen-like protein, and a C5a peptidase. Thus, Mga provides an excellent model system to study global regulatory networks involved in GAS pathogenesis and how they may interact. However, we currently know very little about Mga, including what domains of the protein are critical for its function and how environmental signals control the Mga regulon. The specific aims of this project are: (1) To identify domains of Mga involved in DNA-binding and characterize their role in targeting specific promoters; (2) To determine a consensus Mga binding element for each of the known promoter sites through identification of specific Mga/nucleotide interactions; (3) To investigate whether domains of Mga interact directly with other bacterial components to transduce environmental signals (i.e., is Mga a two-component response regulator?); (4) To identify additional factors required for the environmental regulation of the Mga regulon and assess their role in global virulence regulation. An attractive feature of this proposal is our ability to study Mga both as a purified protein in vitro and as a native molecule in its GAS background. As such, we will be able to thoroughly address key questions of GAS pathogenesis associated closely with the environmental regulation of the Mga regulon. The overall objectives of this proposal are (A) to undertake a structure/function analysis of Mga and determine the mechanisms by which this key GAS virulence regulator contributes to streptococcal disease, and (B) improve our general understanding of regulatory pathways that broadly control virulence in these gram-positive pathogens.