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From Proteopedia
Crystal structure of the yeast metacaspase Yca1
Structural highlights
FunctionMCA1_YEAST Mediates cell death (apoptosis) triggered by oxygen stress, salt stress or chronological aging. Regulated cell death can prevent a release of toxic cellular components, thus avoiding necrotic collapse of the colony, and can also provide nutrients for healthy cells. Therefore, regulated cell death in yeast colonies can be as important for their development as are apoptosis and related processes that occur within metazoa. Promotes the removal of insoluble protein aggregates during normal growth.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] Publication Abstract from PubMedYca1, the only metacaspase in Saccharomyces cerevisiae, is thought to be a clan CD cysteine protease that includes the caspase subfamily. Although yeast is a single cell eukaryote, it can undergo a cell death process reminiscent of apoptosis. Yca1 has been reported to play an important role in the regulation of such apoptotic process. However, the structure and functional mechanism of Yca1 remain largely enigmatic. In this study, we report the crystal structure of the Yca1 metacaspase at 1.7 A resolution, confirming a caspase-like fold. In sharp contrast to canonical caspases, however, Yca1 exists as a monomer both in solution and in the crystals. Canonical caspase contains six beta-strands, with strand beta6 pairing up with beta6 of another caspase molecule to form a homodimerization interface. In Yca1, an extra pair of antiparallel beta-strands forms a continuous beta-sheet with the six caspase-common beta-strands, blocking potential dimerization. Yca1 was reported to undergo autocatalytic processing in yeast; overexpression in bacteria also led to autoprocessing of Yca1 into two fragments. Unexpectedly, we found that both the autocatalytic processing and the proteolytic activity of Yca1 are greatly facilitated by the presence of calcium (Ca(2+)), but not other divalent cations. Our structural and biochemical characterization identifies Yca1 as a Ca(2+)-activated cysteine protease that may cleave specific substrates during stress response in yeast. Crystal structure of the yeast metacaspase Yca1.,Wong AH, Yan C, Shi Y J Biol Chem. 2012 Aug 24;287(35):29251-9. doi: 10.1074/jbc.M112.381806. Epub 2012, Jul 2. PMID:22761449[12] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations 10 reviews cite this structure No citations found See AlsoReferences
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