Cargando…
Degron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria
Conditional proteolytic degradation is an irreversible and highly regulated process that fulfills crucial regulatory functions in all organisms. As proteolytic targets tend to be critical metabolic or regulatory proteins, substrates are targeted for degradation only under appropriate conditions thro...
Autores principales: | , , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Society for Biochemistry and Molecular Biology
2022
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9117542/ https://www.ncbi.nlm.nih.gov/pubmed/35413287 http://dx.doi.org/10.1016/j.jbc.2022.101925 |
_version_ | 1784710333368107008 |
---|---|
author | Whitman, Brendan T. Murray, Cameron R.A. Whitford, Denise S. Paul, Simanta S. Fahlman, Richard P. Glover, Mark J.N. Owttrim, George W. |
author_facet | Whitman, Brendan T. Murray, Cameron R.A. Whitford, Denise S. Paul, Simanta S. Fahlman, Richard P. Glover, Mark J.N. Owttrim, George W. |
author_sort | Whitman, Brendan T. |
collection | PubMed |
description | Conditional proteolytic degradation is an irreversible and highly regulated process that fulfills crucial regulatory functions in all organisms. As proteolytic targets tend to be critical metabolic or regulatory proteins, substrates are targeted for degradation only under appropriate conditions through the recognition of an amino acid sequence referred to as a “degron”. DEAD-box RNA helicases mediate all aspects of RNA metabolism, contributing to cellular fitness. However, the mechanism by which abiotic-stress modulation of protein stability regulates bacterial helicase abundance has not been extensively characterized. Here, we provide in vivo evidence that proteolytic degradation of the cyanobacterial DEAD-box RNA helicase CrhR is conditional, being initiated by a temperature upshift from 20 to 30 °C in the model cyanobacterium, Synechocystis sp. PCC 6803. We show degradation requires a unique, highly conserved, inherently bipartite degron located in the C-terminal extension found only in CrhR-related RNA helicases in the phylum Cyanobacteria. However, although necessary, the degron is not sufficient for proteolysis, as disruption of RNA helicase activity and/or translation inhibits degradation. These results suggest a positive feedback mechanism involving a role for CrhR in expression of a crucial factor required for degradation. Furthermore, AlphaFold structural prediction indicated the C-terminal extension is a homodimerization domain with homology to other bacterial RNA helicases, and mass photometry data confirmed that CrhR exists as a dimer in solution at 22 °C. These structural data suggest a model wherein the CrhR degron is occluded at the dimerization interface but could be exposed if dimerization was disrupted by nonpermissive conditions. |
format | Online Article Text |
id | pubmed-9117542 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | American Society for Biochemistry and Molecular Biology |
record_format | MEDLINE/PubMed |
spelling | pubmed-91175422022-05-21 Degron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria Whitman, Brendan T. Murray, Cameron R.A. Whitford, Denise S. Paul, Simanta S. Fahlman, Richard P. Glover, Mark J.N. Owttrim, George W. J Biol Chem Research Article Conditional proteolytic degradation is an irreversible and highly regulated process that fulfills crucial regulatory functions in all organisms. As proteolytic targets tend to be critical metabolic or regulatory proteins, substrates are targeted for degradation only under appropriate conditions through the recognition of an amino acid sequence referred to as a “degron”. DEAD-box RNA helicases mediate all aspects of RNA metabolism, contributing to cellular fitness. However, the mechanism by which abiotic-stress modulation of protein stability regulates bacterial helicase abundance has not been extensively characterized. Here, we provide in vivo evidence that proteolytic degradation of the cyanobacterial DEAD-box RNA helicase CrhR is conditional, being initiated by a temperature upshift from 20 to 30 °C in the model cyanobacterium, Synechocystis sp. PCC 6803. We show degradation requires a unique, highly conserved, inherently bipartite degron located in the C-terminal extension found only in CrhR-related RNA helicases in the phylum Cyanobacteria. However, although necessary, the degron is not sufficient for proteolysis, as disruption of RNA helicase activity and/or translation inhibits degradation. These results suggest a positive feedback mechanism involving a role for CrhR in expression of a crucial factor required for degradation. Furthermore, AlphaFold structural prediction indicated the C-terminal extension is a homodimerization domain with homology to other bacterial RNA helicases, and mass photometry data confirmed that CrhR exists as a dimer in solution at 22 °C. These structural data suggest a model wherein the CrhR degron is occluded at the dimerization interface but could be exposed if dimerization was disrupted by nonpermissive conditions. American Society for Biochemistry and Molecular Biology 2022-04-10 /pmc/articles/PMC9117542/ /pubmed/35413287 http://dx.doi.org/10.1016/j.jbc.2022.101925 Text en © 2022 The Authors https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). |
spellingShingle | Research Article Whitman, Brendan T. Murray, Cameron R.A. Whitford, Denise S. Paul, Simanta S. Fahlman, Richard P. Glover, Mark J.N. Owttrim, George W. Degron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria |
title | Degron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria |
title_full | Degron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria |
title_fullStr | Degron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria |
title_full_unstemmed | Degron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria |
title_short | Degron-mediated proteolysis of CrhR-like DEAD-box RNA helicases in cyanobacteria |
title_sort | degron-mediated proteolysis of crhr-like dead-box rna helicases in cyanobacteria |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9117542/ https://www.ncbi.nlm.nih.gov/pubmed/35413287 http://dx.doi.org/10.1016/j.jbc.2022.101925 |
work_keys_str_mv | AT whitmanbrendant degronmediatedproteolysisofcrhrlikedeadboxrnahelicasesincyanobacteria AT murraycameronra degronmediatedproteolysisofcrhrlikedeadboxrnahelicasesincyanobacteria AT whitforddenises degronmediatedproteolysisofcrhrlikedeadboxrnahelicasesincyanobacteria AT paulsimantas degronmediatedproteolysisofcrhrlikedeadboxrnahelicasesincyanobacteria AT fahlmanrichardp degronmediatedproteolysisofcrhrlikedeadboxrnahelicasesincyanobacteria AT glovermarkjn degronmediatedproteolysisofcrhrlikedeadboxrnahelicasesincyanobacteria AT owttrimgeorgew degronmediatedproteolysisofcrhrlikedeadboxrnahelicasesincyanobacteria |