TY - JOUR

T1 - The ASC-1 Complex Disassembles Collided Ribosomes

AU - Juszkiewicz, Szymon

AU - Speldewinde, Shaun H.

AU - Wan, Li

AU - Svejstrup, Jesper Q.

AU - Hegde, Ramanujan S.

N1 - Funding Information: We thank V. Chandrasekaran and S. Kraatz for productive discussions, S. Kraatz for generating mutant ASCC2 constructs, and S. Kjaer and R. George of the Crick Institute Structural Biology platform for help with expression of the ASC-1 complex. This work was supported by the UK Medical Research Council (MC_UP_A022_1007 to R.S.H.). Work in the Svejstrup lab was supported by the Francis Crick Institute; FCI receives its core funding from Cancer Research UK grant number FC001166, the UK Medical Research Council grant number FC001166, and the Wellcome Trust grant number FC001166. Work was also supported by the European Research Council (Agreements 693327). S.J. performed, analyzed, and interpreted all experiments shown in the study. S.H.S. and L.W. developed methods to express and purify ASCC and generated purified functional ASCC. J.Q.S. and R.S.H. provided funding and overall guidance of the study. S.J. and R.S.H. conceived the study and wrote the manuscript with input from all authors. The authors declare no competing interests. Funding Information: We thank V. Chandrasekaran and S. Kraatz for productive discussions, S. Kraatz for generating mutant ASCC2 constructs, and S. Kjaer and R. George of the Crick Institute Structural Biology platform for help with expression of the ASC-1 complex. This work was supported by the UK Medical Research Council ( MC_UP_A022_1007 to R.S.H.). Work in the Svejstrup lab was supported by the Francis Crick Institute ; FCI receives its core funding from Cancer Research UK grant number FC001166 , the UK Medical Research Council grant number FC001166 , and the Wellcome Trust grant number FC001166 . Work was also supported by the European Research Council (Agreements 693327 ). Publisher Copyright: © 2020 MRC Laboratory of Molecular Biology

PY - 2020/8/20

Y1 - 2020/8/20

N2 - Translating ribosomes that slow excessively incur collisions with trailing ribosomes. Persistent collisions are detected by ZNF598, a ubiquitin ligase that ubiquitinates sites on the ribosomal 40S subunit to initiate pathways of mRNA and protein quality control. The collided ribosome complex must be disassembled to initiate downstream quality control, but the mechanistic basis of disassembly is unclear. Here, we reconstitute the disassembly of a collided polysome in a mammalian cell-free system. The widely conserved ASC-1 complex (ASCC) containing the ASCC3 helicase disassembles the leading ribosome in an ATP-dependent reaction. Disassembly, but not ribosome association, requires 40S ubiquitination by ZNF598, but not GTP-dependent factors, including the Pelo-Hbs1L ribosome rescue complex. Trailing ribosomes can elongate once the roadblock has been removed and only become targets if they subsequently stall and incur collisions. These findings define the specific role of ASCC during ribosome-associated quality control and identify the molecular target of its activity.

AB - Translating ribosomes that slow excessively incur collisions with trailing ribosomes. Persistent collisions are detected by ZNF598, a ubiquitin ligase that ubiquitinates sites on the ribosomal 40S subunit to initiate pathways of mRNA and protein quality control. The collided ribosome complex must be disassembled to initiate downstream quality control, but the mechanistic basis of disassembly is unclear. Here, we reconstitute the disassembly of a collided polysome in a mammalian cell-free system. The widely conserved ASC-1 complex (ASCC) containing the ASCC3 helicase disassembles the leading ribosome in an ATP-dependent reaction. Disassembly, but not ribosome association, requires 40S ubiquitination by ZNF598, but not GTP-dependent factors, including the Pelo-Hbs1L ribosome rescue complex. Trailing ribosomes can elongate once the roadblock has been removed and only become targets if they subsequently stall and incur collisions. These findings define the specific role of ASCC during ribosome-associated quality control and identify the molecular target of its activity.

KW - ASCC3

KW - helicase

KW - quality control

KW - ribosome

KW - RQC

KW - translation

U2 - 10.1016/j.molcel.2020.06.006

DO - 10.1016/j.molcel.2020.06.006

M3 - Journal article

C2 - 32579943

AN - SCOPUS:85087665071

VL - 79

SP - 603-614.e8

JO - Molecular Cell

JF - Molecular Cell

SN - 1097-2765

IS - 4

ER -