Acinetobacter baumannii Fatty Acid Desaturases Facilitate Survival in Distinct Environments

Maintaining optimal fluidity is essential to ensure adequate membrane structure and function under different environmental conditions. We apply integrated molecular approaches to characterize two desaturases (DesA and DesB) and define their specific roles in unsaturated fatty acid (UFA) production in Acinetobacter baumannii. Using a murine model, we reveal DesA to play a minor role in colonization of the respiratory tract, whereas DesB is important during invasive disease. Furthermore, using transcriptomic and bioinformatic analyses, a global regulator involved in fatty acid homeostasis and members of its regulon are characterized. Collectively, we show that DesA and DesB are primary contributors to UFA production in A. baumannii with infection studies illustrating that these distinct desaturases aid in the bacterium’s ability to survive in multiple host niches. Hence, this study provides novel insights into the fundamentals of A. baumannii lipid biology, which contributes to the versatility of this critical bacterial pathogen.

维持细胞膜的最佳流动性，对于保障其在不同环境条件下具备完整的结构与功能至关重要。本研究采用整合分子生物学方法，对鲍曼不动杆菌(Acinetobacter baumannii)中的两种去饱和酶（desaturases）DesA与DesB进行功能表征，并明确二者在不饱和脂肪酸（UFA）合成中的特异性功能。借助小鼠感染模型，我们发现DesA仅在呼吸道定植过程中发挥次要作用，而DesB则在侵袭性感染过程中扮演关键角色。此外，通过转录组学与生物信息学分析，本研究鉴定出一种参与脂肪酸稳态调控的全局调控因子及其所属调控子（regulon）的成员基因。综合来看，本研究证实DesA与DesB是鲍曼不动杆菌合成不饱和脂肪酸的主要贡献因子；感染实验结果表明，这两种功能迥异的去饱和酶可帮助该细菌在多种宿主生态位中存活。因此，本研究为鲍曼不动杆菌脂质生物学的基础机制提供了全新见解，有助于解析这类关键致病菌的环境适应性。