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bioRxiv · 10.1101/2022.12.22.521501

Structural Basis of Prostaglandin Efflux by MRP4

Pourmal, S.·Green, E.·Bajaj, R.·Chemmama, I.·Knudsen, G.·Gupta, M.·Sali, A.·Cheng, Y.·Craik, C.·Kroetz, D.·Stroud, R.
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Abstract

MRP4 is unique among the C family of ATP-binding cassette transporters for its role in translocating prostanoids, an important group of signaling molecules derived from unsaturated fatty acids. Using a reconstituted system, we report that a pair of prostaglandins (PGs) and the sulfonated-sterol DHEA-S preferentially enhance the ATPase activity of MRP4 over other previously proposed physiological substrates such as cyclic nucleotides or leukotrienes. We determined the cryo-EM structures of nanodisc embedded bovine MRP4 in (i) a nucleotide- and substrate-free state, (ii) in complex with PGE1, (iii) PGE2, and (iv) DHEA-S, and (v) a catalytically dead mutant E1202Q bound to ATP-Mg2+. The substrate-bound structures suggest unique features of the MRP4 binding site that distinguish its specificity for prostanoids from that of the related leukotriene transporter MRP1. The ATP-bound structure is in an outward-occluded conformation, revealing a novel state in the proposed alternate-access mechanism of MRP transport. Our study provides insights into the endogenous function of this versatile efflux transporter.

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Pourmal, S., Green, E., Bajaj, R., Chemmama, I., Knudsen, G., Gupta, M., Sali, A., Cheng, Y., Craik, C., Kroetz, D., Stroud, R.. 2022-12-22. Structural Basis of Prostaglandin Efflux by MRP4. https://doi.org/10.1101/2022.12.22.521501

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