Metabolic adaptation of Acinetobacter baumannii - role of phospholipids in nutrition and infection

膜环境被各种A. baumannii，这就提出了A.鲍曼不动杆菌设法使其新陈代谢适应宿主环境。磷脂酰胆碱（PC）和磷脂酰乙醇胺（PE）是人体细胞膜中含量最丰富的磷脂，是理想的碳源和能源。一组不同的磷脂酶促进磷酸甘油脂的降解。磷脂酶还调节细菌膜的磷脂组成，这对于真核宿主细胞的免疫防御系统的生存至关重要。因此，磷脂酶在病理生物学中起着关键作用。在我们以前的研究中，我们已经确定了三个磷脂酶D（PLD）和两个磷脂酶C（PLC）在A。baumannii协同入侵G.大蜡螟毛虫和肺上皮细胞。接下来，我们将纯化和生化特性的PLD解开他们的行动模式。此外，我们将解决的亚细胞定位和调控的PLD。我们鉴定了胆碱和甘氨酸甜菜碱的多个非依赖性BCC转运蛋白，这表明BCCT除了抗应激保护之外还有另外的作用。一个可能是胆碱作为能量来源的作用，正如我们在A. baylyi。我们将通过对G.大蜡螟和肺上皮细胞培养物中。胆碱和甘氨酸甜菜碱作为潜在的碳源或氮源的作用也将进行分析。此外，胆碱和甘氨酸甜菜碱作为调节代谢物的作用，触发“感知”富含胆碱的宿主环境，从而导致毒力因子的转录调节。我们还在A.鲍曼不动杆菌。后者在细菌中很少被检测到。CL在致病菌的毒力中起重要作用，而MLCL的功能尚不清楚。我们发现PLD 2和PLD 3都是CL和MLCL生产所必需的。接下来，我们将研究PLD 2和PLD 3介导的CL和MLCL的合成。此外，我们的目的是阐明CL和MLCL在两个膜的A。鲍曼不动杆菌。细菌膜脂组成随环境变化而变化。我们将分析宿主感染对PLD表达和PLD产生的影响。此外，PLD2和PLD3过量生产对毒力的影响将得到解决。我们的工作假设是，CL和MLCL的种类繁多的脂质A调节的作用，从而有助于适应和持久性在人类宿主。我们将通过比较A中与脂质A相关的脂肪酸来分析CL和MLCL在脂质A调节中的作用。鲍曼不动杆菌PLD 2/PLD 3突变体和野生型细胞。

Membranous environments are colonized by various strains of A. baumannii, which raises the question on how A. baumannii manages to adapt its metabolism to the host environment. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) are the most abundant phospholipids found in human cell membranes and make them good candidates as carbon and energy source. The degradation of phosphoglycerolipids is facilitated by a set of different phospholipases. Phospholipases also modulate the phospholipid composition of bacterial membranes, which is crucial to survive the immune defence system of eukaryotic host cells. Therefore, phospholipases play a key role in pathobiology. In our preceding studies we have identified three phospholipases D (PLDs) and two phospholipases C (PLCs) in A. baumannii acting in concerted manner in invasion of G. mellonella caterpillars and lung epithelial cells. Next, we will purify and biochemically characterize the PLDs to unravel their mode of action. Moreover, we will address the subcellular localization and regulation of the PLDs. We identified multiple osmo-independent BCC transporter for choline and glycine betaine which suggests an additional role of the BCCTs other than osmostress protection. One could be a role of choline as energy source as we have found in A. baylyi. We will address the role of choline and glycine betaine uptake in host adaptation by mutant studies in G. mellonella and in lung epithelial cell cultures. The role of choline and glycine betaine as potential carbon or nitrogen source will also be analyzed. Moreover, a role of choline and glycine betaine as regulatory metabolites triggering the "sensing" of choline rich host environments thereby leading to transcriptional modulation of virulence factors will be addressed. We have also identified a broad variety of cardiolipins (CL) and monolysocardiolipins (MLCL) in A. baumannii. The latter has been very rarely detected in bacteria. CLs are known to play important roles in virulence of pathogenic bacteria whereas the function of MLCLs is unclear. We found that PLD2 and PLD3 are both essential for CL and MLCL production. Next, we will investigate the PLD2- and PLD3-mediated synthesis of CL and MLCL. Moreover, we aim to elucidate the distribution of CL and MLCL in both membranes of A. baumannii. Membrane lipid composition of bacteria changes in response to environmental changes. We will analyze the effect of host infection on pld expression and PLD production. Moreover, the effect of PLD2 and PLD3 overproduction on virulence will be addressed. Our working hypothesis is that the large variety of CLs and MLCLs plays a role of lipid A modulation thereby contributing to adaptation and persistence in the human host. We will analyze the role of CL and MLCL in lipid A modulation by comparison of fatty acids linked to lipid A in A. baumannii pld2/pld3 mutants and in wildtype cells.