Structure and ion-release mechanism of PIB-4-type ATPases.

Christina Grønberg,Annette Duelli,Pontus Gourdon,Pin Lyu,Dhani Ram Mahato,Nina Salustros,Tristan Croll,Gabriela Godaly,Viktoria Bågenholm,Jonas Eriksson,Komal Umashankar Rao,Magnus Andersson,Gabriele Meloni,Qiaoxia Hu,Domhnall Iain Henderson,Kaituo Wang,Elena Longhin

doi:10.7554/elife.73124

Christina Grønberg, Annette Duelli + Show 15 more

Open Access

https://doi.org/10.7554/elife.73124

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Abstract

Transition metals, such as zinc, are essential micronutrients in all organisms, but also highly toxic in excessive amounts. Heavy-metal transporting P-type (PIB) ATPases are crucial for homeostasis, conferring cellular detoxification and redistribution through transport of these ions across cellular membranes. No structural information is available for the PIB-4-ATPases, the subclass with the broadest cargo scope, and hence even their topology remains elusive. Here, we present structures and complementary functional analyses of an archetypal PIB-4-ATPase, sCoaT from Sulfitobacter sp. NAS14-1. The data disclose the architecture, devoid of classical so-called heavy-metal-binding domains (HMBDs), and provide fundamentally new insights into the mechanism and diversity of heavy-metal transporters. We reveal several novel P-type ATPase features, including a dual role in heavy-metal release and as an internal counter ion of an invariant histidine. We also establish that the turnover of PIB-ATPases is potassium independent, contrasting to many other P-type ATPases. Combined with new inhibitory compounds, our results open up for efforts in for example drug discovery, since PIB-4-ATPases function as virulence factors in many pathogens.

Highlights

The ability to adapt to environmental changes in heavy metal levels is paramount for all cells, as these elements are essential for a range of cellular processes and yet toxic at elevated concentrations[1, 2]
Cd2+ dependent ATPase activity, while Co2+ only stimulated ATP-hydrolysis at high ion concentrations (Figure 2 – figure supplement 1). This is in partial agreement with the ion range profile previously reported for sCoaT, as higher Co2+ sensitivity has been detected using a different functional assay and different experimental conditions[18] (Figure 2 – figure supplement 1)
; 90 % of the Collectively, the first structure of a PIB-4-type ATPase reveals the topology of PIB-4

Summary

Introduction

The ability to adapt to environmental changes in heavy metal levels is paramount for all cells, as these elements are essential for a range of cellular processes and yet toxic at elevated concentrations[1, 2]. Despite a shared overall architecture, the PIB-1 and PIB-2 structures suggested significantly different types of entry and exit pathways, hinting at unique translocation mechanisms for each PIB group similar molecular adaptions have taken place in PIB-4-ATPases to handle the unique array of cargos. To address these fundamental questions, we determined structures of a PIB-4-ATPase in different states and validated our findings using in vitro functional characterization

Results & Discussion

Conclusion

Materials and methods