Analysis of MGA protein from the Streptococcus pyogenes

描述(申请人提供)：A组链球菌(化脓性链球菌，GAS)是一种具有巨大医学意义的细菌病原体 人类，导致各种疾病综合征，其严重程度从 轻微到危及生命。MGA是一种与DNA结合的GAS蛋白，可激活 几个关键毒力基因的转录对变化的响应 环境条件，可能通过与其他监管机构的相互作用 单元中的组件。MGA规则编码的产品是 GAS在宿主中的存活，包括抗吞噬的M蛋白、M样蛋白 免疫球蛋白结合蛋白，补体的分泌抑制物，a 类胶原蛋白和C5a多肽酶。因此，MGA提供了一个极好的 研究GAS发病机制的全球调控网络的模型系统 以及它们可能如何相互作用。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，以及如何 环境信号控制着MGA调节子。这样做的具体目的是 项目是：(1)确定参与DNA结合的MGA结构域和 描述它们在针对特定启动子方面的作用；(2)确定 每个已知启动子位点的共识MGA结合元件通过 鉴定特定的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成分相互作用 传递环境信号(即，MGA是否是双分量响应 监管机构？)；(4)确定环境所需的其他因素 MGA调节子的调节及其在全球毒力中的作用 监管。这项建议的一个吸引人的特点是我们能够研究MGA 无论是作为体外纯化的蛋白质还是作为其气体中的天然分子 背景资料。因此，我们将能够彻底解决天然气的关键问题 MGA的发病机制与环境调节密切相关 正规药。这项建议的总体目标是：(A)开展 对MGA的结构/功能进行分析，并确定其作用机制 关键毒力调节因子导致链球菌疾病，以及(B) 提高我们对广泛控制的调控途径的总体理解 这些革兰氏阳性病原体的毒性。

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.