Structure and ion-release mechanism of PIB-4-type ATPases
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, and provides 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 turn-over 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 e.g. drug discovery, since PIB-4-ATPases function as virulence factors in many pathogens.
Data availability
Atomic coordinates and structure factors for the sCoaT AlF4-- and BeF3--stabilized crystal structures have been deposited at the Protein Data Bank (PDB) under accession codes 7QBZ and 7QC0.
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Structure and ion-release mechanism of PIB-4-type ATPasesProtein Data Bank, 7QBZ.
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Structure and ion-release mechanism of PIB-4-type ATPasesProtein Data Bank, 7QC0.
Article and author information
Author details
Funding
Novo Nordisk Fonden (NNF18SA0034956)
- Christina Grønberg
Lundbeckfonden (R313-2019-774,R218-2016-1548,R133-A12689)
- Pontus Gourdon
Knut och Alice Wallenbergs Stiftelse (2020.0194,2015.0131)
- Pontus Gourdon
Carlsbergfondet (CF15-0542,2013_01_0641)
- Pontus Gourdon
Novo Nordisk Fonden (NNF13OC0007471)
- Pontus Gourdon
Brodrene Hartmann (A29519)
- Pontus Gourdon
Agnes og Poul Friis Fond
- Pontus Gourdon
Augustinus Fonden (16-1992)
- Pontus Gourdon
Crafoord (20180652,20170818)
- Pontus Gourdon
Per-Eric and Ulla Schyberg (38267)
- Pontus Gourdon
Swedish Research Council (2016-04474)
- Pontus Gourdon
The memorial foundation of manufacturer Vilhelm Pedersen and wife - and the Aarhus Wilson consortium
- Christina Grønberg
The Independent Research Fund Denmark (9039-00273A)
- Pontus Gourdon
China Scholarship Council
- Qiaoxia Hu
Carl Tryggers Stiftelse för Vetenskaplig Forskning (CTS 17:22)
- Dhani Ram Mahato
Swedish Research Council Starting Grant (2016-03610)
- Magnus Andersson
Robert A. Welke Cancer Research Foundation (AT-1935-20170325 and AT-2073-20210327)
- Gabriele Meloni
National Institute of General Medical Sciences (R35GM128704))
- Gabriele Meloni
National Science Foundation (CHE- 2045984)
- Gabriele Meloni
Swedish Heart-Lung Foundation (20200378)
- Gabriela Godaly
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Grønberg et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Further reading
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The conformational ensemble and function of intrinsically disordered proteins (IDPs) are sensitive to their solution environment. The inherent malleability of disordered proteins, combined with the exposure of their residues, accounts for this sensitivity. One context in which IDPs play important roles that are concomitant with massive changes to the intracellular environment is during desiccation (extreme drying). The ability of organisms to survive desiccation has long been linked to the accumulation of high levels of cosolutes such as trehalose or sucrose as well as the enrichment of IDPs, such as late embryogenesis abundant (LEA) proteins or cytoplasmic abundant heat-soluble (CAHS) proteins. Despite knowing that IDPs play important roles and are co-enriched alongside endogenous, species-specific cosolutes during desiccation, little is known mechanistically about how IDP-cosolute interactions influence desiccation tolerance. Here, we test the notion that the protective function of desiccation-related IDPs is enhanced through conformational changes induced by endogenous cosolutes. We find that desiccation-related IDPs derived from four different organisms spanning two LEA protein families and the CAHS protein family synergize best with endogenous cosolutes during drying to promote desiccation protection. Yet the structural parameters of protective IDPs do not correlate with synergy for either CAHS or LEA proteins. We further demonstrate that for CAHS, but not LEA proteins, synergy is related to self-assembly and the formation of a gel. Our results suggest that functional synergy between IDPs and endogenous cosolutes is a convergent desiccation protection strategy seen among different IDP families and organisms, yet the mechanisms underlying this synergy differ between IDP families.
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