Prabudiansyah Irfan, Orädd Fredrik, Magkakis Konstantinos, Pounot Kevin, Levantino Matteo, Andersson Magnus
Department of Chemistry, Umeå University, Umeå, Sweden.
ESRF, The European Synchrotron CS40220, 38043 Grenoble Cedex 9, France.
Sci Adv. 2024 Oct 11;10(41):eadp2916. doi: 10.1126/sciadv.adp2916.
Calcium (Ca) signaling is fundamental to cellular processes in both eukaryotic and prokaryotic organisms. While the mechanisms underlying eukaryotic Ca transport are well documented, an understanding of prokaryotic transport remains nascent. LMCA1, a Ca adenosine triphosphatase (ATPase) from , has emerged as a prototype for elucidating structure and dynamics in prokaryotic Ca transport. Here, we used a multidisciplinary approach integrating kinetics, structure, and dynamics to unravel the intricacies of LMCA1 function. A cryo-electron microscopy (cryo-EM) structure of a Ca-bound E1 state showed ion coordination by Asp, Asn, and Glu. Time-resolved x-ray solution scattering experiments identified phosphorylation as the rate-determining step. A cryo-EM E2P state structure exhibited remarkable similarities to a SERCA1a E2-P* state, which highlights the essential role of the unique P-A domain interface in enhancing dephosphorylation rates and reconciles earlier proposed mechanisms. Our study underscores the distinctiveness between eukaryotic and prokaryotic Ca ATPase transport systems and positions LMCA1 as a promising drug target for developing antimicrobial strategies.
钙（Ca）信号传导对于真核生物和原核生物的细胞过程都至关重要。虽然真核生物钙转运的潜在机制已有充分记载，但对原核生物钙转运的了解仍处于起步阶段。来自[具体来源未提及]的钙腺苷三磷酸酶（ATP酶）LMCA1已成为阐明原核生物钙转运结构和动力学的原型。在这里，我们采用了一种结合动力学、结构和动力学的多学科方法来揭示LMCA1功能的复杂性。结合钙的E1状态的冷冻电子显微镜（cryo-EM）结构显示了由天冬氨酸、天冬酰胺和谷氨酸进行的离子配位。时间分辨X射线溶液散射实验确定磷酸化是速率决定步骤。冷冻电子显微镜E2P状态结构与SERCA1a E2-P*状态表现出显著相似性，这突出了独特的P-A结构域界面在提高去磷酸化速率方面的重要作用，并与早期提出的机制相契合。我们的研究强调了真核生物和原核生物钙ATP酶转运系统之间的差异，并将LMCA1定位为开发抗菌策略的一个有前景的药物靶点。
