Urner Leonhard H, Fiorentino Francesco, Shutin Denis, Sauer Joshua B, Agasid Mark T, El-Baba Tarick J, Bolla Jani R, Stansfeld Phillip J, Robinson Carol V
TU Dortmund University, Department of Chemistry and Chemical Biology, Otto-Hahn-Strasse 6, Dortmund 44227, Germany.
Kavli Institute for Nanoscience Discovery, South Parks Road, Oxford OX1 3QU, United Kingdom.
J Am Chem Soc. 2024 Apr 11;146(16):11025-30. doi: 10.1021/jacs.3c14358.
Lipopolysaccharide (LPS) is vital for maintaining the outer membrane barrier in Gram-negative bacteria. LPS is also frequently obtained in complex with the inner membrane proteins after detergent purification. The question of whether or not LPS binding to inner membrane proteins not involved in outer membrane biogenesis reflects native lipid environments remains unclear. Here, we leverage the control of the hydrophilic-lipophilic balance and packing parameter concepts to chemically tune detergents that can be used to qualitatively differentiate the degree to which proteins copurify with phospholipids (PLs) and/or LPS. Given the scalable properties of these detergents, we demonstrate a detergent fine-tuning that enables the facile investigation of intact proteins and their complexes with lipids by native mass spectrometry (nMS). We conclude that LPS, a lipid that is believed to be important for outer membranes, can also affect the activity of membrane proteins that are currently not assigned to be involved in outer membrane biogenesis. Our results deliver a scalable detergent chemistry for a streamlined biophysical characterization of protein-lipid interactions, provide a rationale for the high affinity of LPS-protein binding, and identify noncanonical associations between LPS and inner membrane proteins with relevance for membrane biology and antibiotic research.
脂多糖（LPS）对于维持革兰氏阴性菌的外膜屏障至关重要。在去污剂纯化后，LPS还经常与内膜蛋白形成复合物。LPS与不参与外膜生物合成的内膜蛋白结合是否反映天然脂质环境的问题仍不清楚。在此，我们利用亲水-亲脂平衡和堆积参数概念的控制来化学调节去污剂，这些去污剂可用于定性区分蛋白质与磷脂（PLs）和/或LPS共纯化的程度。鉴于这些去污剂的可扩展特性，我们展示了一种去污剂微调方法，该方法能够通过天然质谱（nMS）轻松研究完整蛋白质及其与脂质的复合物。我们得出结论，LPS这种被认为对外膜很重要的脂质，也会影响目前未被认定参与外膜生物合成的膜蛋白的活性。我们的结果为蛋白质-脂质相互作用的简化生物物理表征提供了一种可扩展的去污剂化学方法，为LPS-蛋白质结合的高亲和力提供了理论依据，并确定了LPS与内膜蛋白之间与膜生物学和抗生素研究相关的非经典关联。
