8UC6

Calpain-7:IST1 Complex

Summary for 8UC6

• Entry DOI: 10.2210/pdb8uc6/pdb
• Descriptor: Calpain-7, IST1 homolog (3 entities in total)
• Functional Keywords: escrt-iii, abscission, peptide binding protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 4
• Total formula weight: 47010.29

Authors

Paine, E.,Whitby, F.G.,Hill, C.P.,Sunquist, W.I. (deposition date: 2023-09-25, release date: 2023-10-25, Last modification date: 2024-05-15)

Primary citation

Paine, E.L.,Skalicky, J.J.,Whitby, F.G.,Mackay, D.R.,Ullman, K.S.,Hill, C.P.,Sundquist, W.I.
The Calpain-7 protease functions together with the ESCRT-III protein IST1 within the midbody to regulate the timing and completion of abscission.
Elife, 12:-, 2023

PubMed Abstract: The Endosomal Sorting Complexes Required for Transport (ESCRT) machinery mediates the membrane fission step that completes cytokinetic abscission and separates dividing cells. Filaments composed of ESCRT-III subunits constrict membranes of the intercellular bridge midbody to the abscission point. These filaments also bind and recruit cofactors whose activities help execute abscission and/or delay abscission timing in response to mitotic errors via the NoCut/Abscission checkpoint. We previously showed that the ESCRT-III subunit IST1 binds the cysteine protease Calpain-7 (CAPN7) and that CAPN7 is required for both efficient abscission and NoCut checkpoint maintenance (Wenzel et al., 2022). Here, we report biochemical and crystallographic studies showing that the tandem microtubule-interacting and trafficking (MIT) domains of CAPN7 bind simultaneously to two distinct IST1 MIT interaction motifs. Structure-guided point mutations in either CAPN7 MIT domain disrupted IST1 binding in vitro and in cells, and depletion/rescue experiments showed that the CAPN7-IST1 interaction is required for (1) CAPN7 recruitment to midbodies, (2) efficient abscission, and (3) NoCut checkpoint arrest. CAPN7 proteolytic activity is also required for abscission and checkpoint maintenance. Hence, IST1 recruits CAPN7 to midbodies, where its proteolytic activity is required to regulate and complete abscission.

PubMed: 37772788
DOI: 10.7554/eLife.84515

Experimental method

X-RAY DIFFRACTION (2.701 Å)