Table_1_Acyl Carrier Protein 3 Is Involved in Oxidative Stress Response in Pseudomonas aeruginosa.PDF

The human opportunistic pathogen Pseudomonas aeruginosa expresses three acyl carrier proteins (ACPs): AcpP, Acp1, and Acp3. The function of AcpP in membrane fatty acid synthesis (FAS) was confirmed recently, but the physiological roles of Acp1 and Acp3 remain unclear. To address this, we investigated the physiological role of Acp3 in P. aeruginosa. We found that expression of Acp3 dramatically increases in the log phase of cell growth and that its transcription is under the control of the QS regulators LasR and RhlR. Deletion of acp3 from P. aeruginosa strain PAO1 results in thicker biofilm formation, increased resistance of the strain to hydrogen peroxide, and higher persistence in a mouse infection model. Tandem affinity purification (TAP) experiments revealed several novel protein-binding partners of Acp3, including KatA, the major catalase in P. aeruginosa. Acp3 was found to repress the catalase activity of KatA and, consistent with inhibition by Acp3, less reactive oxygen species are present in the acp3 deletion strain. Overall, our study reveals that Acp3 has a distinct function from that of the canonical AcpP and may be involved in the oxidative stress response.

人类条件致病菌铜绿假单胞菌（Pseudomonas aeruginosa）表达三种酰基载体蛋白（acyl carrier protein，ACP）：AcpP、Acp1与Acp3。此前学界已证实AcpP在膜脂肪酸合成（fatty acid synthesis，FAS）中的功能，但Acp1与Acp3的生理功能仍未明确。为厘清这一科学问题，本研究针对铜绿假单胞菌中Acp3的生理功能展开探究。本研究发现，Acp3的表达在细胞对数生长期显著上调，且其转录受群体感应（Quorum Sensing，QS）调控因子LasR与RhlR的调控。从铜绿假单胞菌PAO1菌株中敲除acp3基因，会导致该菌株形成更厚的生物被膜、对过氧化氢的抗性增强，且在小鼠感染模型中的定植持久性更高。串联亲和纯化（tandem affinity purification，TAP）实验发现了Acp3的多个新型蛋白结合伴侣，其中包括铜绿假单胞菌的主要过氧化氢酶KatA。研究证实Acp3可抑制KatA的过氧化氢酶活性；与之相符的是，acp3敲除菌株内的活性氧（reactive oxygen species）水平显著降低。综上，本研究揭示Acp3与经典的AcpP功能迥异，且可能参与氧化应激应答。