Membrane Transport Group, Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo, P.O. Box 1137, Blindern, 0318 Oslo, Norway; Enzyme and Protein Chemistry, Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, 2800 Kgs. Lyngby, Denmark.
Department of Chemistry, University of Antwerp, Campus Groenenborger, Groenenborgerlaan 171, G.V. 418, 2020 Antwerpen, Belgium.
Biochim Biophys Acta Mol Cell Res. 2024 Jan;1871(1):119614. doi: 10.1016/j.bbamcr.2023.119614. Epub 2023 Oct 23.
The bacterial magnesium transporter A (MgtA) is a specialized P-type ATPase important for Mg import into the cytoplasm; disrupted magnesium homeostasis is linked to intrinsic ribosome instability and antibacterial resistance in Salmonella strains. Here, we show that MgtA has functional specificity for cardiolipin 18:1. Still, it reaches maximum activity only in combination with cardiolipin 16:0, equivalent to the major components of native cardiolipin found in E. coli membranes. Native mass spectrometry indicates the presence of two binding sites for cardiolipin, agreeing with the kinetic studies revealing that a cooperative relationship likely exists between the two cardiolipin variants. This is the first experimental evidence of cooperative effects between lipids of the same class, with only minor variations in their acyl chain composition, acting on a membrane protein. In summary, our results reveal that MgtA exhibits a highly complex interaction with one cardiolipin 18:1 and one cardiolipin 16:0, affecting protein activity and stability, contributing to our understanding of the particular interactions between lipid environment and membrane proteins. Further, a better understanding of Mg homeostasis in bacteria, due to its role as a virulence regulator, will provide further insights into the regulation and mechanism of bacterial infections.
细菌镁转运蛋白 A（MgtA）是一种重要的 P 型 ATP 酶，专门用于将镁导入细胞质；镁离子内环境稳态的破坏与沙门氏菌菌株中固有核糖体不稳定性和抗菌耐药性有关。在这里，我们表明 MgtA 对 18:1 心磷脂具有功能特异性。尽管如此，它只有与 16:0 心磷脂结合时才能达到最大活性，这相当于大肠杆菌膜中天然心磷脂的主要成分。天然质谱表明存在两个心磷脂结合位点，这与动力学研究结果一致，该结果表明两种心磷脂变体之间可能存在协同关系。这是关于同一类脂质之间协同作用的第一个实验证据，它们的酰基链组成只有微小差异，作用于膜蛋白。总之，我们的研究结果表明，MgtA 与一个 18:1 心磷脂和一个 16:0 心磷脂表现出高度复杂的相互作用，影响蛋白质的活性和稳定性，有助于我们理解脂质环境与膜蛋白之间的特殊相互作用。此外，由于其作为毒力调节剂的作用，更好地了解细菌中的镁离子内环境稳态将进一步深入了解细菌感染的调控和机制。
