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Updated: Jun 22, 2026

A Colorimetric Assay that Specifically Measures Granzyme B Proteolytic Activity: Hydrolysis of Boc-Ala-Ala-Asp-S-Bzl
Published on: November 28, 2014
The cytotoxic T lymphocyte protease granzyme A cleaves and inactivates poly(adenosine 5'-diphosphate-ribose)
Pengcheng Zhu1, Denis Martinvalet, Dipanjan Chowdhury
1Immune Disease Institute and Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA.
Abstract:
Granzyme A (GzmA) in killer cells induces caspase-independent programmed cell death. In this study, we show that GzmA cleaves the DNA damage sensor poly(adenosine 5'-diphosphate-ribose) polymerase-1 (PARP-1) after Lys(498) in its automodification domain, separating the DNA binding domain from the catalytic domain, which interferes with repair of GzmA-induced DNA damage and enhances susceptibility to GzmA-mediated death. Overexpressing K498A PARP-1 reduces GzmA-mediated death and drives dying cells to necrosis rather than apoptosis. Conversely, inhibiting or genetically disrupting PARP-1 enhances cell vulnerability. The N-terminal GzmA cleavage fragment of PARP-1 acts as a PARP-1 dominant negative, binding to DNA and blocking DNA repair. Disrupting PARP-1, which is also a caspase target, is therefore required for efficient apoptosis by both caspase-independent and caspase-dependent pathways.
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