Sensing central metabolic stress

描述(申请人提供)：在大肠杆菌和可能的其他细菌中，中央代谢的高能中间体[例如乙酰磷酸(ACP)和乙酰辅酶A(AcCoA)]似乎至少部分地通过称为双组分信号转导(2CST)反应调节因子(RR)的信号蛋白质子集来控制全球基因表达。ACP和acCoA的高能状态使它们都成为很好的供体：ACP可以捐赠其磷酸基，而acCoA可以捐赠其乙酰基。再加上它们在新陈代谢中的中心位置，这些能力使ACP和acCoA非常适合指示营养状态，从而影响各种细胞过程。这项提议将检验以下假设的关键方面。暴露在过量碳中的细胞经历了与其不能足够快地循环辅酶A(CoA)有关的中心代谢压力。由于CoA的存在数量有限，因此acCoA：CoA比率变大。为了循环代谢必需的辅酶A，一些多余的乙酰基从辅酶A传递到无机磷酸。这一过程导致了ACP的合成，有人建议将其磷酰基捐赠给2CSTRRs的子集。可替换地或同时，可以将其他乙酰基直接给RRs的第二子集，从而改变它们的功能。这一假说主要基于以下观察：(I)细胞在生长过程中操纵acCoA和ACP的比例，并对碳源的质量和数量做出反应。(Ii)细胞对两种高能中枢代谢物浓度的变化做出全局反应；(Iii)对ACP的反应取决于至少一个RR的作用，甚至可能更多；(Iv)两个启动子，每个依赖于不同的RR，似乎对acCoA池的状态做出反应；以及(V)acCoA已被证明将其乙酰基捐赠给两个纯化的RR。2CST途径调控与生物膜发育和发病相关的各种过程。由于人类不表达2CST通路，ACP和acCoA修饰RRs的能力是抗微生物策略的主要靶点。与公共卫生相关：这项提议将检验这一假设，即乙酰辅酶A和乙酰磷酸是中枢代谢的高能中间体，可以分别通过乙酰化或磷酸化进行修饰，从而改变信号蛋白的功能，这些信号蛋白有助于不同病原体的生物膜发育和毒力。因为人类不表达这些被称为反应调节器的信号蛋白，所以这些相互作用是抗微生物策略的主要目标。

DESCRIPTION (provided by applicant): In Escherichia coli -- and likely other bacteria -- high-energy intermediates of central metabolism [e.g. acetyl phosphate (acP) and acetyl-coenzyme A (acCoA)] appear to control global gene expression -- at least in part - through a subset of signaling proteins called two-component signal transduction (2CST) response regulators (RRs). The high-energy status of acP and acCoA makes each an excellent donor: acP can donate its phosphoryl group, while acCoA can donate its acetyl group. Coupled with their central position in metabolism, these abilities make acP and acCoA ideally suited to indicate nutritional status and thereby impact a variety of cellular processes. This proposal will test key aspects of the following hypothesis. Cells exposed to excess carbon experience a central metabolic stress associated with their inability to recycle coenzymeA (CoA) rapidly enough. Because CoA is present in limiting amounts, the acCoA:CoA ratio becomes large. To recycle the metabolically essential CoA, some of the excess acetyl groups pass from CoA to inorganic phosphate. This process results in the synthesis of acP, which has been proposed to donate its phosphoryl group to a subset of 2CSTRRs. Alternatively or simultaneously, other acetyl groups can be donated directly to a second subset of RRs, thereby altering their function. This hypothesis is broadly based on the following observations: (i) cells manipulate the ratio of acCoA and acP during growth and in response to the quality and quantity of carbon source. (ii) cells respond globally to variations in the concentrations of both high-energy central metabolites; (iii) the response to acP depends on the action of at least one RR and likely more; (iv) two promoters, each dependent on a different RR, appear to respond to the status of the acCoA pool; and (v) acCoA has been shown to donate its acetyl group to 2 purified RRs. 2CST pathways regulate diverse processes associated with biofilm development and pathogenesis. Because humans do not express 2CST pathways, the abilities of acP and acCoA to modify RRs represent a prime target for anti-microbial strategies. PUBLIC HEALTH RELEVANCE: This proposal will test the hypothesis that acetyl coenzyme A and acetyl phosphate, high-energy intermediates of central metabolism, can modify - by acetylation or phosphorylation, respectively - and thereby alter the function of signaling proteins that contribute to biofilm development by and virulence of diverse pathogens. Because humans do not express these signaling proteins, called response regulators, these interactions represent a prime target for anti-microbial strategies.