Apoptosis is a regulated form of cell death essential to the removal of unwanted cells. At its core, a family of cysteine peptidases named caspases cleave key proteins allowing cell death to occur. To do so, each caspase catalytic pocket recognizes preferred amino acid sequences resulting in proteolysis, but some also use exosites to select and cleave important proteins efficaciously. Such exosites have been found in a few caspases, notably caspase-7 that has a lysine patch (K38KKK) that binds RNA, which acts as a bridge to RNA-binding proteins favoring proximity between the peptidase and its substrates resulting in swifter cleavage. Although caspase-7 interaction with RNA has been identified, in-depth characterization of this interaction is lacking. In this study, using in vitro cleavage assays, we determine that RNA concentration and length affect the cleavage of RNA-binding proteins. Additionally, using binding assays and RNA sequencing, we found that caspase-7 binds RNA molecules regardless of their type, sequence, or structure. Moreover, we demonstrate that the N-terminal peptide of caspase-7 reduces the affinity of the peptidase for RNA, which translates into slower cleavages of RNA-binding proteins. Finally, employing engineered heterodimers, we show that a caspase-7 dimer can use both exosites simultaneously to increase its affinity to RNA because a heterodimer with only one exosite has reduced affinity for RNA and cleavage efficacy. These findings shed light on a mechanism that furthers substrate recognition by caspases and provides potential insight into its regulation during apoptosis.
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July 2021
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SMCHD1 is an epigenetic regulator that mediates gene expression silencing at targeted sites across the genome. In this issue Gurzau and colleagues (pp. 2555–2569) use biophysical techniques to we demonstrate that the SMCHD1 ATPase undergoes dimerization in a process that is dependent on both the N-terminal Ubiquitin-like domain and ATP binding. The cover image shows immunofluorescence with DAPI staining in cyan and SMCHD1 showing in yellow. Scale bars are 20 µm. Image provided by James M. Murphy.
Research Article|
July 16 2021
Characterization of caspase-7 interaction with RNA
Alexandre Desroches;
Alexandre Desroches
Conceptualization, Data curation, Formal analysis, Methodology, Writing - original draft, Writing - review & editing
Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
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Jean-Bernard Denault
Conceptualization, Funding acquisition, Writing - original draft, Writing - review & editing
Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
Correspondence: Jean-Bernard Denault (Jean-Bernard.Denault@USherbrooke.ca)
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Publisher: Portland Press Ltd
Received:
May 18 2021
Revision Received:
June 18 2021
Accepted:
June 22 2021
Accepted Manuscript online:
June 22 2021
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2021 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2021
Biochem J (2021) 478 (13): 2681–2696.
Article history
Received:
May 18 2021
Revision Received:
June 18 2021
Accepted:
June 22 2021
Accepted Manuscript online:
June 22 2021
Citation
Alexandre Desroches, Jean-Bernard Denault; Characterization of caspase-7 interaction with RNA. Biochem J 16 July 2021; 478 (13): 2681–2696. doi: https://doi.org/10.1042/BCJ20210366
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