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Auto‐proteolysis of Type 1 Metacaspases in Schizophyllum commune
Author(s) -
Cummings Brianna Paige,
Fox Kristin M.
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.781.2
Subject(s) - proteolysis , chemistry , biochemistry , histidine , schizophyllum commune , active site , caspase , calcium , enzyme , apoptosis , programmed cell death , organic chemistry
Apoptosis is a specialized form of programmed cell that occurs under conditions such as stress, aging, and development. A key marker of apoptosis is the presence of caspases that cleave peptide bonds after aspartate residues via a catalytic histidine/cystine dyad. A group of related enzymes called metacaspases are found in plants, protozoa and fungi. Like caspases, they contain an active site histidine/cystine dyad and have a similar protein fold, yet they show preference for lysine and arginine residues and many require calcium for cleavage. Furthermore, Type I metacaspases contain a proline‐rich N‐terminal prodomain that is typically cleaved to achieve the fully active form. In some Type I metacaspases, continued auto‐proteolysis is observed after the prodomain is removed. Within the fungus Schizophyllum commune genome five type I metacaspases ( Sc MC1‐5) have been characterized and expressed with and without the prodomain. Additionally, optimal pH and calcium concentrations have been determined for each of these metacaspases. To further understand the auto‐proteolysis of these metacaspases, attention was focused on Sc MC1. A time course has been established over which Sc MC1, in the presence of calcium, auto‐processes to form a 40kDa fragment. Fluorescent activity assays over the same time course have shown a decrease in overall activity on small peptide substrates of the incubated enzyme. Additionally, the H211Q/C267A active site double mutant form of Sc MC1 showed decreased activity and no auto‐proteolysis upon incubation with calcium. Lastly, incubation of wild‐type Sc MC2‐4 with the double mutant Sc MC1 showed no proteolysis of Sc MC1, indicating cleavage of Sc MC1 by other Type I metacaspases does not occur. These results have furthered our understanding of metacaspase activation and function, and ultimately their role in fungal apoptosis. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .