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Sterol metabolism in the filasterean Capsaspora owczarzaki has features that resemble both fungi and animals

By Sebastián R. Najle, María Celeste Molina, Iñaki Ruiz-Trillo and Antonio D. Uttaro


Sterols are essential for several physiological processes in most eukaryotes. Sterols regulate membrane homeostasis and participate in different signalling pathways not only as precursors of steroid hormones and vitamins, but also through its role in the formation of lipid rafts. Two major types of sterols, cholesterol and ergosterol, have been described so far in the opisthokonts, the clade that comprise animals, fungi and their unicellular relatives. Cholesterol predominates in derived bilaterians, whereas ergosterol is what generally defines fungi. We here characterize, by a combination of bioinformatic and biochemical analyses, the sterol metabolism in the filasterean Capsaspora owczarzaki, a close unicellular relative of animals that is becoming a model organism. We found that C. owczarzaki sterol metabolism combines enzymatic activities that are usually considered either characteristic of fungi or exclusive to metazoans. Moreover, we observe a differential transcriptional regulation of this metabolism across its life cycle. Thus, C. owczarzaki alternates between synthesizing 7-dehydrocholesterol de novo, which happens at the cystic stage, and the partial conversion—via a novel pathway—of incorporated cholesterol into ergosterol, the characteristic fungal sterol, in the filopodial and aggregative stages.This work was supported by grants from Agencia Nacional de Promoción Científica y Tecnológica (ANPCYT-PICT 2012-1301 and ANPCYT-PICT 2014-1311) to A.D.U; a European Research Council Consolidator Grant (ERC-2012-Co -616960) grant and a grant (BFU2014-57779-P) from Ministerio de Economía y Competitividad (MINECO) to I.R.-T., the latter co-funded by the European Regional Development Fund (fondos FEDER). S.R.N. and A.D.U. are members of Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina. We also acknowledge financial support from Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (Project 2014 SGR 619).Peer reviewe

Topics: Capsaspora, Sterol metabolism, Transcriptional regulation, Opisthokonts, Cholesterol, Ergosterol
Publisher: 'The Royal Society'
Year: 2016
DOI identifier: 10.1098/rsob.160029
OAI identifier:
Provided by: Digital.CSIC

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