Abstract
Metacaspases are cysteine specific proteases implicated in cell-signalling, stress acclimation and programmed cell death (PCD) pathways in plants, fungi, protozoa, bacteria and algae. We investigated metacaspase-like gene expression and biochemical activity in the bloom-forming, N 2 -fixing, marine cyanobacterium Trichodesmium, which undergoes PCD under low iron and high-light stress. We examined these patterns with respect to in-silico analyses of protein domain architectures that revealed a diverse array of regulatory domains within Trichodesmium metacaspases-like (TeMC) proteins. Experimental manipulations of laboratory cultures and oceanic surface blooms of Trichodesmium from the South Pacific Ocean triggered PCD under Fe-limitation and high light along with enhanced TeMC activity and upregulated expression of diverse TeMC representatives containing different regulatory domains. Furthermore, TeMC activity was significantly and positively correlated with caspase-like activity, which has been routinely observed to increase with PCD induction in Trichodesmium. Although both TeMC and caspase-like activities were stimulated upon PCD induction, inhibitor treatments of these proteolytic activities provided further evidence of largely distinct substrate specificities, even though some inhibitory crossover was observed. Our findings are the first results linking metacaspase expression and activity in PCD induced mortality in Trichodesmium. Yet, the role/s and specific activities of these different proteins remain to be elucidated.
Original language | English |
---|---|
Pages (from-to) | 667-681 |
Number of pages | 15 |
Journal | Environmental Microbiology |
Volume | 21 |
Issue number | 2 |
DOIs | |
State | Published - 1 Feb 2019 |
Bibliographical note
Funding Information:This work was conducted as part of the United States-Israel Binational Science Foundation (BSF) grant 2008048 to IBF and KDB, a collaborative grant from MOST Israel and the High Council for Science and Technology (HCST)-France to IBF, and GIF funding No. 1133/2011 to IBF. This research was also funded in part by the Gordon and Betty Moore Foundation through Grant GBMF3789 to KDB. We thank Sophie Bonnet, Thierry Moutin, Captain and crew of the R/V Alis and the entire team of the VAHINE project in New Caledonia. Thanks especially to E. Rahav for his assistance throughout the New Caledonia experiment and to L. Haramati and H. Elifantz for methodological and analytical guidance. This work was in partial fulfilment of the PhD thesis requirements for D. Spungin at Bar Ilan University.
Publisher Copyright:
© 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.
ASJC Scopus subject areas
- Microbiology
- Ecology, Evolution, Behavior and Systematics