Cargando…

A Role for the Proteasome Alpha2 Subunit N-Tail in Substrate Processing

The proteolytic active sites of the 26S proteasome are sequestered within the catalytic chamber of its 20S core particle (CP). Access to this chamber is through a narrow channel defined by the seven outer α subunits. In the resting state, the N-termini of neighboring α subunits form a gate blocking...

Descripción completa

Detalles Bibliográficos
Autores principales: Sahu, Indrajit, Bajorek, Monika, Tan, Xiaolin, Srividya, Madabhushi, Krutauz, Daria, Reis, Noa, Osmulski, Pawel A., Gaczynska, Maria E., Glickman, Michael H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10046698/
https://www.ncbi.nlm.nih.gov/pubmed/36979414
http://dx.doi.org/10.3390/biom13030480
_version_ 1785013738148986880
author Sahu, Indrajit
Bajorek, Monika
Tan, Xiaolin
Srividya, Madabhushi
Krutauz, Daria
Reis, Noa
Osmulski, Pawel A.
Gaczynska, Maria E.
Glickman, Michael H.
author_facet Sahu, Indrajit
Bajorek, Monika
Tan, Xiaolin
Srividya, Madabhushi
Krutauz, Daria
Reis, Noa
Osmulski, Pawel A.
Gaczynska, Maria E.
Glickman, Michael H.
author_sort Sahu, Indrajit
collection PubMed
description The proteolytic active sites of the 26S proteasome are sequestered within the catalytic chamber of its 20S core particle (CP). Access to this chamber is through a narrow channel defined by the seven outer α subunits. In the resting state, the N-termini of neighboring α subunits form a gate blocking access to the channel. The attachment of the activators or regulatory particles rearranges the blocking α subunit N-termini facilitating the entry of substrates. By truncating or mutating each of the participating α N-termini, we report that whereas only a few N-termini are important for maintaining the closed gate, all seven N-termini participate in the open gate. Specifically, the open state is stabilized by a hydrogen bond between an invariant tyrosine (Y) in each subunit with a conserved aspartate (D) in its counterclockwise neighbor. The lone exception is the α1–α2 pair leaving a gap in the ring circumference. The third residue (X) of this YD(X) motif aligns with the open channel. Phenylalanine at this position in the α2 subunit comes in direct contact with the translocating substrate. Consequently, deletion of the α2 N-terminal tail attenuates proteolysis despite the appearance of an open gate state. In summary, the interlacing N-terminal YD(X) motifs regulate both the gating and translocation of the substrate.
format Online
Article
Text
id pubmed-10046698
institution National Center for Biotechnology Information
language English
publishDate 2023
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-100466982023-03-29 A Role for the Proteasome Alpha2 Subunit N-Tail in Substrate Processing Sahu, Indrajit Bajorek, Monika Tan, Xiaolin Srividya, Madabhushi Krutauz, Daria Reis, Noa Osmulski, Pawel A. Gaczynska, Maria E. Glickman, Michael H. Biomolecules Article The proteolytic active sites of the 26S proteasome are sequestered within the catalytic chamber of its 20S core particle (CP). Access to this chamber is through a narrow channel defined by the seven outer α subunits. In the resting state, the N-termini of neighboring α subunits form a gate blocking access to the channel. The attachment of the activators or regulatory particles rearranges the blocking α subunit N-termini facilitating the entry of substrates. By truncating or mutating each of the participating α N-termini, we report that whereas only a few N-termini are important for maintaining the closed gate, all seven N-termini participate in the open gate. Specifically, the open state is stabilized by a hydrogen bond between an invariant tyrosine (Y) in each subunit with a conserved aspartate (D) in its counterclockwise neighbor. The lone exception is the α1–α2 pair leaving a gap in the ring circumference. The third residue (X) of this YD(X) motif aligns with the open channel. Phenylalanine at this position in the α2 subunit comes in direct contact with the translocating substrate. Consequently, deletion of the α2 N-terminal tail attenuates proteolysis despite the appearance of an open gate state. In summary, the interlacing N-terminal YD(X) motifs regulate both the gating and translocation of the substrate. MDPI 2023-03-05 /pmc/articles/PMC10046698/ /pubmed/36979414 http://dx.doi.org/10.3390/biom13030480 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Sahu, Indrajit
Bajorek, Monika
Tan, Xiaolin
Srividya, Madabhushi
Krutauz, Daria
Reis, Noa
Osmulski, Pawel A.
Gaczynska, Maria E.
Glickman, Michael H.
A Role for the Proteasome Alpha2 Subunit N-Tail in Substrate Processing
title A Role for the Proteasome Alpha2 Subunit N-Tail in Substrate Processing
title_full A Role for the Proteasome Alpha2 Subunit N-Tail in Substrate Processing
title_fullStr A Role for the Proteasome Alpha2 Subunit N-Tail in Substrate Processing
title_full_unstemmed A Role for the Proteasome Alpha2 Subunit N-Tail in Substrate Processing
title_short A Role for the Proteasome Alpha2 Subunit N-Tail in Substrate Processing
title_sort role for the proteasome alpha2 subunit n-tail in substrate processing
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10046698/
https://www.ncbi.nlm.nih.gov/pubmed/36979414
http://dx.doi.org/10.3390/biom13030480
work_keys_str_mv AT sahuindrajit arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT bajorekmonika arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT tanxiaolin arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT srividyamadabhushi arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT krutauzdaria arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT reisnoa arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT osmulskipawela arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT gaczynskamariae arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT glickmanmichaelh arolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT sahuindrajit rolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT bajorekmonika rolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT tanxiaolin rolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT srividyamadabhushi rolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT krutauzdaria rolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT reisnoa rolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT osmulskipawela rolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT gaczynskamariae rolefortheproteasomealpha2subunitntailinsubstrateprocessing
AT glickmanmichaelh rolefortheproteasomealpha2subunitntailinsubstrateprocessing