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

RUIZ-TRILLO I; MOLINA M.C.; NAJLE S.; UTTARO AD

Open Biology

Royal Society

Año: 2016 p. 160029 - 160029

Sterols are essential for several physiological processes in most eukaryotes.Sterols regulate both membrane homeostasis and participate in different signallingpathways not only as precursors of steroid hormones and vitamins,but also through its role in the formation of lipid rafts. Two major types ofsterols, 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 whatgenerally defines fungi. We here characterized, by a combination of bioinformaticand biochemical analyses, the sterols metabolism in the filastereanCapsaspora owczarzaki, a close unicellular relative of animals that is becominga model organism. We found that C. owczarzaki sterol metabolism combinesenzymatic activities that are usually considered either characteristic of fungior exclusive to metazoans. Moreover, we observe a differential transcriptionalregulation of this metabolism across its life cycle. Thus, C. owczarzaki alternatesbetween synthesizing 7-dehydrocholesterol de novo, which happens at thecystic stage, and the partial conversion?via a novel pathway?of incorporatedcholesterol into ergosterol, the characteristic fungal sterol, in thefilopodial and aggregative stages.