9q1e
Cryo-EM structure of a membrane transport protein
Structural highlights
FunctionA0A1V0NGB6_LACLL Mediates magnesium influx to the cytosol.[ARBA:ARBA00003954] Publication Abstract from PubMedP-type ATPases represent an evolutionarily conserved superfamily of ion, lipid, and peptide pumps found across all domains of life. Among the substrates transported by P-type ATPases, Mg(2+) is of critical importance in bacterial, fungal, and plant cellular homeostasis. A bacterial P-type ATPase found in Gram-negative bacteria, Mg(2+) transporter A (MgtA), facilitates the transport of Mg(2+) from the periplasm to the cytoplasm under conditions of Mg(2+) starvation. MgtA is a cardiolipin-sensitive integral membrane ion-transporter that scavenges Mg(2+) during bacterial infection and pathogenesis. Here, we determined cryo-EM structures of MgtA capturing three distinct states along the Mg(2+) transport cycle, including a phosphorylated E2-P intermediate (2.6 A resolution), an E1-like conformation stabilized by the peptide regulator MgtR (2.7 A resolution), and an E1-like ATP-bound state (2.8 A resolution). These three conformations reveal the binding of Mg(2+) in the transmembrane domain coordinated in a novel site involving Ser(702) and Asn(706) on M5, Ser(773) and Asp(777) on M7, and Ser(821) and Thr(824) on M8. In the E2-P conformation, the phosphate analog BeF(3) is bound in close proximity to the catalytic aspartate, Asp(361), suggesting that it represents a covalent aspartylphosphate intermediate. In the presence of AMPPCP, Mg(2+) remains bound in the transmembrane domain and the ATP analog is bound in a catalytically competent conformation. Overall, the structures reveal distinct steps in the transport cycle of MgtA compared to other P-type ATPases, as well as lipid binding sites that fill gaps in our understanding of transport regulation. Distinct transport cycle and lipid regulation of a Mg(2+)-transporting P-type ATPase, MgtA.,Khan MB, Primeau JO, Chaudhuri-Basu P, Bergdoll L, Renault L, Morth JP, Lemieux MJ, Young HS Res Sq [Preprint]. 2026 May 4:rs.3.rs-9173029. doi: 10.21203/rs.3.rs-9173029/v1. PMID:42147146[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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