RRC ID 32130
Author Kashiyama Y, Yokoyama A, Kinoshita Y, Shoji S, Miyashiya H, Shiratori T, Suga H, Ishikawa K, Ishikawa A, Inouye I, Ishida K, Fujinuma D, Aoki K, Kobayashi M, Nomoto S, Mizoguchi T, Tamiaki H.
Title Ubiquity and quantitative significance of detoxification catabolism of chlorophyll associated with protistan herbivory.
Journal Proc Natl Acad Sci U S A
Abstract Chlorophylls are essential components of the photosynthetic apparati that sustain all of the life forms that ultimately depend on solar energy. However, a drawback of the extraordinary photosensitizing efficiency of certain chlorophyll species is their ability to generate harmful singlet oxygen. Recent studies have clarified the catabolic processes involved in the detoxification of chlorophylls in land plants, but little is understood about these strategies in aquatic ecosystem. Here, we report that a variety of heterotrophic protists accumulate the chlorophyll a catabolite 13(2),17(3)-cyclopheophorbide a enol (cPPB-aE) after their ingestion of algae. This chlorophyll derivative is nonfluorescent in solution, and its inability to generate singlet oxygen in vitro qualifies it as a detoxified catabolite of chlorophyll a. Using a modified analytical method, we show that cPPB-aE is ubiquitous in aquatic environments, and it is often the major chlorophyll a derivative. Our findings suggest that cPPB-aE metabolism is one of the most important, widely distributed processes in aquatic ecosystems. Therefore, the herbivorous protists that convert chlorophyll a to cPPB-aE are suggested to play more significant roles in the modern oceanic carbon flux than was previously recognized, critically linking microscopic primary producers to the macroscopic food web and carbon sequestration in the ocean.
Volume 109(43)
Pages 17328-35
Published 2012-10-23
DOI 10.1073/pnas.1207347109
PII 1207347109
PMID 22949677
PMC PMC3491467
MeSH Biological Evolution Chlorophyll / metabolism* Herbivory* Photosynthesis Plants / metabolism*
IF 9.412
Times Cited 34
Algae NIES-281