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Open Biol. 2017 May;7(5). pii: 170042. doi: 10.1098/rsob.170042.

Phosphatase UBLCP1 controls proteasome assembly.

Sun S1, Liu S1, Zhang Z2,3, Zeng W1, Sun C2, Tao T4, Lin X2,3, Feng XH5,2,3.

Author information

1
Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
2
Michael E. DeBakey, Department of Surgery, Houston, TX, USA.
3
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.
4
State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China.
5
Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China xhfeng@zju.edu.cn xfeng@bcm.edu.

Abstract

Ubiquitin-like domain-containing C-terminal domain phosphatase 1 (UBLCP1), an FCP/SCP phosphatase family member, was identified as the first proteasome phosphatase. UBLCP1 binds to proteasome subunit Rpn1 and dephosphorylates the proteasome in vitro However, it is still unclear which proteasome subunit(s) are the bona fide substrate(s) of UBLCP1 and the precise mechanism for proteasome regulation remains elusive. Here, we show that UBLCP1 selectively binds to the 19S regulatory particle (RP) through its interaction with Rpn1, but not the 20S core particle (CP) or the 26S proteasome holoenzyme. In the RP, UBLCP1 dephosphorylates the subunit Rpt1, impairs its ATPase activity, and consequently disrupts the 26S proteasome assembly, yet it has no effects on the RP assembly from precursor complexes. The Rpn1-binding and phosphatase activities of UBLCP1 are essential for its function on Rpt1 dephosphorylation and proteasome activity both in vivo and in vitro Our study establishes the essential role of the UBLCP1/Rpn1/Rpt1 complex in regulating proteasome assembly.

KEYWORDS:

CTD phosphatase; UBLCP1; phosphorylation; proteasome

PMID:
28539385
PMCID:
PMC5451543
DOI:
10.1098/rsob.170042
[Indexed for MEDLINE]
Free PMC Article

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