Zinc-binding triggers a conformational-switch in the cullin-3 substrate adaptor protein KEAP1 that controls transcription factor NRF2

Michael McMahon (Lead / Corresponding author), Samuel R. Swift, John D. Hayes (Lead / Corresponding author)

Research output: Contribution to journalArticle

4 Citations (Scopus)
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Abstract

Kelch-like ECH-associated protein 1 (Keap1) is a cullin-3 (Cul3)-RING ubiquitin ligase (CRL) adaptor/scaffold protein that enables cells to adapt to environmental stressors because modification of certain of its Cys residues initiates de-repression of the NF-E2 p45-related factor-2 (Nrf2) transcription factor. Thus, in normal unstressed cells, the cytoprotective Nrf2 is continuously ubiquitylated by CRLKeap1, thereby ensuring that Nrf2 is efficiently degraded by the proteasome and expression of Nrf2 target genes restricted. By contrast, this process is attenuated in stressed cells, allowing Nrf2 protein to accumulate in the nucleus and induce genes that promote cell survival. It remains unclear how Keap1 senses stress. Previously, we suggested that release of free Zn2+ from damaged proteins represents an endogenous 'danger' signal recognized by Keap1. However, the existence of a Zn2+ sensor in Keap1 is not widely acknowledged. We now present data that support the hypothesis that Keap1 directly senses Zn2+ through a cluster of amino-acids that include His-225, Cys-226, and Cys-613. We show that this mechanism does not require p62/sequestosome-1, an autophagy adaptor protein implicated in metal(loid) sensing by Keap1. Moreover, using a genetically-encoded FRET reporter, we present evidence that binding of Zn2+ triggers a conformational switch in Keap1. The altered conformation of Keap1 is envisaged to perturb the architecture of CRLKeap1, such that bound Nrf2 becomes mis-aligned with respect to the ubiquitin-charged E2 enzyme. These data are consistent with the notion that Keap1 possesses a Zn2+ sensor whose triggering distorts its structure of in a fashion that inhibits ubiquitylation of Nrf2 upon CRLKeap1.

Original languageEnglish
Pages (from-to)45-57
Number of pages13
JournalToxicology and Applied Pharmacology
Volume360
Early online date24 Sep 2018
DOIs
Publication statusPublished - 1 Dec 2018

Fingerprint

Cullin Proteins
NF-E2-Related Factor 2
Zinc
Transcription Factors
Switches
Substrates
Proteins
Ubiquitin
Kelch-Like ECH-Associated Protein 1
Ubiquitination
Autophagy
Genes
Proteasome Endopeptidase Complex
Ligases
Cell Survival
Sensors
Metals
Scaffolds

Keywords

  • Danger signal
  • KEAP1
  • NRF2
  • Ubiquitylation
  • Zinc

Cite this

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title = "Zinc-binding triggers a conformational-switch in the cullin-3 substrate adaptor protein KEAP1 that controls transcription factor NRF2",
abstract = "Kelch-like ECH-associated protein 1 (Keap1) is a cullin-3 (Cul3)-RING ubiquitin ligase (CRL) adaptor/scaffold protein that enables cells to adapt to environmental stressors because modification of certain of its Cys residues initiates de-repression of the NF-E2 p45-related factor-2 (Nrf2) transcription factor. Thus, in normal unstressed cells, the cytoprotective Nrf2 is continuously ubiquitylated by CRLKeap1, thereby ensuring that Nrf2 is efficiently degraded by the proteasome and expression of Nrf2 target genes restricted. By contrast, this process is attenuated in stressed cells, allowing Nrf2 protein to accumulate in the nucleus and induce genes that promote cell survival. It remains unclear how Keap1 senses stress. Previously, we suggested that release of free Zn2+ from damaged proteins represents an endogenous 'danger' signal recognized by Keap1. However, the existence of a Zn2+ sensor in Keap1 is not widely acknowledged. We now present data that support the hypothesis that Keap1 directly senses Zn2+ through a cluster of amino-acids that include His-225, Cys-226, and Cys-613. We show that this mechanism does not require p62/sequestosome-1, an autophagy adaptor protein implicated in metal(loid) sensing by Keap1. Moreover, using a genetically-encoded FRET reporter, we present evidence that binding of Zn2+ triggers a conformational switch in Keap1. The altered conformation of Keap1 is envisaged to perturb the architecture of CRLKeap1, such that bound Nrf2 becomes mis-aligned with respect to the ubiquitin-charged E2 enzyme. These data are consistent with the notion that Keap1 possesses a Zn2+ sensor whose triggering distorts its structure of in a fashion that inhibits ubiquitylation of Nrf2 upon CRLKeap1.",
keywords = "Danger signal, KEAP1, NRF2, Ubiquitylation, Zinc",
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note = "We thank Cancer Research UK (grants C4909/A5942 and C4909/A9990) and the Medical Research Council (grant MR/N009851/1) for funding our work.",
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Zinc-binding triggers a conformational-switch in the cullin-3 substrate adaptor protein KEAP1 that controls transcription factor NRF2. / McMahon, Michael (Lead / Corresponding author); Swift, Samuel R.; Hayes, John D. (Lead / Corresponding author).

In: Toxicology and Applied Pharmacology, Vol. 360, 01.12.2018, p. 45-57.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Zinc-binding triggers a conformational-switch in the cullin-3 substrate adaptor protein KEAP1 that controls transcription factor NRF2

AU - McMahon, Michael

AU - Swift, Samuel R.

AU - Hayes, John D.

N1 - We thank Cancer Research UK (grants C4909/A5942 and C4909/A9990) and the Medical Research Council (grant MR/N009851/1) for funding our work.

PY - 2018/12/1

Y1 - 2018/12/1

N2 - Kelch-like ECH-associated protein 1 (Keap1) is a cullin-3 (Cul3)-RING ubiquitin ligase (CRL) adaptor/scaffold protein that enables cells to adapt to environmental stressors because modification of certain of its Cys residues initiates de-repression of the NF-E2 p45-related factor-2 (Nrf2) transcription factor. Thus, in normal unstressed cells, the cytoprotective Nrf2 is continuously ubiquitylated by CRLKeap1, thereby ensuring that Nrf2 is efficiently degraded by the proteasome and expression of Nrf2 target genes restricted. By contrast, this process is attenuated in stressed cells, allowing Nrf2 protein to accumulate in the nucleus and induce genes that promote cell survival. It remains unclear how Keap1 senses stress. Previously, we suggested that release of free Zn2+ from damaged proteins represents an endogenous 'danger' signal recognized by Keap1. However, the existence of a Zn2+ sensor in Keap1 is not widely acknowledged. We now present data that support the hypothesis that Keap1 directly senses Zn2+ through a cluster of amino-acids that include His-225, Cys-226, and Cys-613. We show that this mechanism does not require p62/sequestosome-1, an autophagy adaptor protein implicated in metal(loid) sensing by Keap1. Moreover, using a genetically-encoded FRET reporter, we present evidence that binding of Zn2+ triggers a conformational switch in Keap1. The altered conformation of Keap1 is envisaged to perturb the architecture of CRLKeap1, such that bound Nrf2 becomes mis-aligned with respect to the ubiquitin-charged E2 enzyme. These data are consistent with the notion that Keap1 possesses a Zn2+ sensor whose triggering distorts its structure of in a fashion that inhibits ubiquitylation of Nrf2 upon CRLKeap1.

AB - Kelch-like ECH-associated protein 1 (Keap1) is a cullin-3 (Cul3)-RING ubiquitin ligase (CRL) adaptor/scaffold protein that enables cells to adapt to environmental stressors because modification of certain of its Cys residues initiates de-repression of the NF-E2 p45-related factor-2 (Nrf2) transcription factor. Thus, in normal unstressed cells, the cytoprotective Nrf2 is continuously ubiquitylated by CRLKeap1, thereby ensuring that Nrf2 is efficiently degraded by the proteasome and expression of Nrf2 target genes restricted. By contrast, this process is attenuated in stressed cells, allowing Nrf2 protein to accumulate in the nucleus and induce genes that promote cell survival. It remains unclear how Keap1 senses stress. Previously, we suggested that release of free Zn2+ from damaged proteins represents an endogenous 'danger' signal recognized by Keap1. However, the existence of a Zn2+ sensor in Keap1 is not widely acknowledged. We now present data that support the hypothesis that Keap1 directly senses Zn2+ through a cluster of amino-acids that include His-225, Cys-226, and Cys-613. We show that this mechanism does not require p62/sequestosome-1, an autophagy adaptor protein implicated in metal(loid) sensing by Keap1. Moreover, using a genetically-encoded FRET reporter, we present evidence that binding of Zn2+ triggers a conformational switch in Keap1. The altered conformation of Keap1 is envisaged to perturb the architecture of CRLKeap1, such that bound Nrf2 becomes mis-aligned with respect to the ubiquitin-charged E2 enzyme. These data are consistent with the notion that Keap1 possesses a Zn2+ sensor whose triggering distorts its structure of in a fashion that inhibits ubiquitylation of Nrf2 upon CRLKeap1.

KW - Danger signal

KW - KEAP1

KW - NRF2

KW - Ubiquitylation

KW - Zinc

U2 - 10.1016/j.taap.2018.09.033

DO - 10.1016/j.taap.2018.09.033

M3 - Article

C2 - 30261176

VL - 360

SP - 45

EP - 57

JO - Toxicology and Applied Pharmacology

JF - Toxicology and Applied Pharmacology

SN - 0041-008X

ER -