Familial and somatic BAP1 mutations inactivate ASXL1/2-mediated allosteric regulation of BAP1 deubiquitinase by targeting multiple independent domains

Hongzhuang Peng, Jeremy Prokop, Jayashree Karar, Kyewon Park, Li Cao, J. William Harbour, Anne M. Bowcock, S. Bruce Malkowicz, Mitchell Cheung, Joseph R. Testa, Frank J. Rauscher

Research output: Contribution to journalArticle

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Abstract

Deleterious mutations of the ubiquitin carboxy-terminal hydrolase BAP1 found in cancers are predicted to encode inactive truncated proteins, suggesting that loss of enzyme function is a primary tumorigenic mechanism. However, many tumors exhibit missense mutations or in-frame deletions or insertions, often outside the functionally critical UCH domain in this tumor suppressor protein. Thus, precisely how these mutations inactivate BAP1 is unknown. Here, we show how these mutations affect BAP1 interactions with the Polycomb group-like protein, ASXL2, using combinations of computational modeling technology, molecular biology, and in vitro reconstitution biochemistry. We found that the BAP1-ASXL2 interaction is direct and high affinity, occurring through the ASXH domain of ASXL2, an obligate partner for BAP1 enzymatic activity. The ASXH domain was the minimal domain for binding the BAP1 ULD domain, and mutations on the surfaces of predicted helices of ASXH abolished BAP1 association and stimulation of BAP1 enzymatic activity. The BAP1-UCH, BAP1-ULD, and ASXH domains formed a cooperative stable ternary complex required for deubiquitination. We defined four classes of alterations in BAP1 outside the UCH domain, each failing to productively recruit ASXH to the wild-type BAP1 catalytic site via the ULD, resulting in loss of BAP1 ubiquitin hydrolase activity. Our results indicate that many BAP1 mutations act allosterically to inhibit ASXH binding, thereby leading to loss of enzyme activity. Small-molecule approaches to reactivate latent wild-type UCH activity of these mutants might be therapeutically viable.

Original languageEnglish (US)
Pages (from-to)1200-1213
Number of pages14
JournalCancer Research
Volume78
Issue number5
DOIs
StatePublished - Mar 1 2018

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Allosteric Regulation
Mutation
Ubiquitin Thiolesterase
Polycomb-Group Proteins
Tumor Suppressor Proteins
Hydrolases
Missense Mutation
Enzymes
Ubiquitin
Biochemistry
Molecular Biology
Catalytic Domain
Neoplasms
Deubiquitinating Enzymes
Technology
Proteins

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Familial and somatic BAP1 mutations inactivate ASXL1/2-mediated allosteric regulation of BAP1 deubiquitinase by targeting multiple independent domains. / Peng, Hongzhuang; Prokop, Jeremy; Karar, Jayashree; Park, Kyewon; Cao, Li; William Harbour, J.; Bowcock, Anne M.; Malkowicz, S. Bruce; Cheung, Mitchell; Testa, Joseph R.; Rauscher, Frank J.

In: Cancer Research, Vol. 78, No. 5, 01.03.2018, p. 1200-1213.

Research output: Contribution to journalArticle

Peng, H, Prokop, J, Karar, J, Park, K, Cao, L, William Harbour, J, Bowcock, AM, Malkowicz, SB, Cheung, M, Testa, JR & Rauscher, FJ 2018, 'Familial and somatic BAP1 mutations inactivate ASXL1/2-mediated allosteric regulation of BAP1 deubiquitinase by targeting multiple independent domains', Cancer Research, vol. 78, no. 5, pp. 1200-1213. https://doi.org/10.1158/0008-5472.CAN-17-2876
Peng, Hongzhuang ; Prokop, Jeremy ; Karar, Jayashree ; Park, Kyewon ; Cao, Li ; William Harbour, J. ; Bowcock, Anne M. ; Malkowicz, S. Bruce ; Cheung, Mitchell ; Testa, Joseph R. ; Rauscher, Frank J. / Familial and somatic BAP1 mutations inactivate ASXL1/2-mediated allosteric regulation of BAP1 deubiquitinase by targeting multiple independent domains. In: Cancer Research. 2018 ; Vol. 78, No. 5. pp. 1200-1213.
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AU - Peng, Hongzhuang

AU - Prokop, Jeremy

AU - Karar, Jayashree

AU - Park, Kyewon

AU - Cao, Li

AU - William Harbour, J.

AU - Bowcock, Anne M.

AU - Malkowicz, S. Bruce

AU - Cheung, Mitchell

AU - Testa, Joseph R.

AU - Rauscher, Frank J.

PY - 2018/3/1

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N2 - Deleterious mutations of the ubiquitin carboxy-terminal hydrolase BAP1 found in cancers are predicted to encode inactive truncated proteins, suggesting that loss of enzyme function is a primary tumorigenic mechanism. However, many tumors exhibit missense mutations or in-frame deletions or insertions, often outside the functionally critical UCH domain in this tumor suppressor protein. Thus, precisely how these mutations inactivate BAP1 is unknown. Here, we show how these mutations affect BAP1 interactions with the Polycomb group-like protein, ASXL2, using combinations of computational modeling technology, molecular biology, and in vitro reconstitution biochemistry. We found that the BAP1-ASXL2 interaction is direct and high affinity, occurring through the ASXH domain of ASXL2, an obligate partner for BAP1 enzymatic activity. The ASXH domain was the minimal domain for binding the BAP1 ULD domain, and mutations on the surfaces of predicted helices of ASXH abolished BAP1 association and stimulation of BAP1 enzymatic activity. The BAP1-UCH, BAP1-ULD, and ASXH domains formed a cooperative stable ternary complex required for deubiquitination. We defined four classes of alterations in BAP1 outside the UCH domain, each failing to productively recruit ASXH to the wild-type BAP1 catalytic site via the ULD, resulting in loss of BAP1 ubiquitin hydrolase activity. Our results indicate that many BAP1 mutations act allosterically to inhibit ASXH binding, thereby leading to loss of enzyme activity. Small-molecule approaches to reactivate latent wild-type UCH activity of these mutants might be therapeutically viable.

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