Sensing central metabolic stress

描述（由申请人提供）：在大肠杆菌和可能的其他细菌中，中心代谢的高能中间体[例如乙酰磷酸（acP）和乙酰辅酶A (acCoA)]似乎通过称为双组分信号转导（2CST）反应调节因子（RRs）的信号蛋白子集控制全局基因表达-至少部分。acP和acCoA的高能状态使它们各自成为优秀的供体：acP可以提供它的磷酰基，而acCoA可以提供它的乙酰基。再加上它们在新陈代谢中的中心地位，这些能力使acP和acCoA非常适合用于指示营养状况，从而影响各种细胞过程。这个提议将检验以下假设的关键方面。暴露于过量碳的细胞会经历与它们无法足够快地回收辅酶a （CoA）相关的中枢代谢应激。由于CoA的含量有限，acCoA:CoA的比值变得很大。为了回收代谢必需的辅酶a，一些多余的乙酰基从辅酶a转化为无机磷酸盐。这一过程导致acP的合成，有人提出acP将其磷酸化基团提供给2CSTRRs的一个子集。另外，其他乙酰基也可以直接加入到RRs的第二个亚群中，从而改变它们的功能。这一假设大致基于以下观察：(i)细胞在生长过程中操纵acCoA和acP的比例，以响应碳源的质量和数量。（ii）细胞对两种高能中枢代谢物浓度的变化作出全局性反应；（iii）对acP的反应须视乎最少一名或可能多名违法者的行动而定；（iv）两个启动子，各自依赖于不同的RR，似乎对acCoA池的状态做出反应；(v) acCoA已被证明将其乙酰基提供给2个纯化的rs。2CST通路调节与生物膜发育和发病机制相关的多种过程。由于人类不表达2CST通路，acP和acCoA修饰RRs的能力代表了抗微生物策略的主要目标。公共卫生相关性：本提案将验证乙酰辅酶A和乙酰磷酸这两种中心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性。因为人类不表达这些被称为反应调节因子的信号蛋白，这些相互作用代表了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.