| Title: | Biochemical Characterization of a Novel Redox-Regulated Metacaspase in a Marine Diatom |
| Author(s): | Graff van Creveld S; Ben-Dor S; Mizrachi A; Alcolombri U; Hopes A; Mock T; Rosenwasser S; Vardi A; |
| Address: | "Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel. School of Oceanography, University of Washington, Seattle, WA, United States. Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel. Department of Civil, Environmental and Geomatic Engineering, Institute for Environmental Engineering, Swiss Federal Institute of Technology, Zurich, Switzerland. School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom. Robert H. Smith Faculty of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Jerusalem, Israel" |
| DOI: | 10.3389/fmicb.2021.688199 |
| ISSN/ISBN: | 1664-302X (Print) 1664-302X (Electronic) 1664-302X (Linking) |
| Abstract: | "Programmed cell death (PCD) in marine microalgae was suggested to be one of the mechanisms that facilitates bloom demise, yet its molecular components in phytoplankton are unknown. Phytoplankton are completely lacking any of the canonical components of PCD, such as caspases, but possess metacaspases. Metacaspases were shown to regulate PCD in plants and some protists, but their roles in algae and other organisms are still elusive. Here, we identified and biochemically characterized a type III metacaspase from the model diatom Phaeodactylum tricornutum, termed PtMCA-IIIc. Through expression of recombinant PtMCA-IIIc in E. coli, we revealed that PtMCA-IIIc exhibits a calcium-dependent protease activity, including auto-processing and cleavage after arginine. Similar metacaspase activity was detected in P. tricornutum cell extracts. PtMCA-IIIc overexpressing cells exhibited higher metacaspase activity, while CRISPR/Cas9-mediated knockout cells had decreased metacaspase activity compared to WT cells. Site-directed mutagenesis of cysteines that were predicted to form a disulfide bond decreased recombinant PtMCA-IIIc activity, suggesting its enhancement under oxidizing conditions. One of those cysteines was oxidized, detected in redox proteomics, specifically in response to lethal concentrations of hydrogen peroxide and a diatom derived aldehyde. Phylogenetic analysis revealed that this cysteine-pair is unique and widespread among diatom type III metacaspases. The characterization of a cell death associated protein in diatoms provides insights into the evolutionary origins of PCD and its ecological significance in algal bloom dynamics" |
| Keywords: | Phaeodactylum tricornutum diatom infochemicals metacaspase phytoplankton programmed cell death reactive oxygen species redox-regulation; |
| Notes: | "PubMed-not-MEDLINEGraff van Creveld, Shiri Ben-Dor, Shifra Mizrachi, Avia Alcolombri, Uria Hopes, Amanda Mock, Thomas Rosenwasser, Shilo Vardi, Assaf eng Switzerland 2021/09/28 Front Microbiol. 2021 Sep 8; 12:688199. doi: 10.3389/fmicb.2021.688199. eCollection 2021" |
