Sterol metabolism in the filasterean Capsaspora owczarzaki has features that resemble both fungi and animals
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2016-07-01
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The Royal Society
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Descripción
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. Choles terol predominates in derived bilaterians, whereas ergosterol is what generally
defines fungi. We here characterize, by a combination of bioinformatic and bio chemical 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.
Palabras clave
Capsaspora, Sterol Metabolism, Transcriptional Regulation, Opisthokonts, Cholesterol, Ergosterol