functional characterization of the chlamydomonas reinhardtii erg3 ortholog, a gene involved in the biosynthesis of ergosterol衣藻的功能描述reinhardtii erg3直接同源,麦角固醇的生物合成有关的基因.pdfVIP

Functional Characterization of the Chlamydomonas reinhardtii ERG3 Ortholog, a Gene Involved in the Biosynthesis of Ergosterol 2 1 1 1 1 Kristy M. Brumfield , James V. Moroney , Thomas S. Moore , Tiffany A. Simms , David Donze * 1 Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America, 2 Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, United States of America Abstract Background: The predominant sterol in the membranes of the alga Chlamydomonas reinhardtii is ergosterol, which is commonly found in the membranes of fungi, but is rarely found in higher plants. Higher plants and fungi synthesize sterols by different pathways, with plants producing cycloartenol as a precursor to end-product sterols, while non- photosynthesizing organisms like yeast and humans produce lanosterol as a precursor. Analysis of the C. reinhardtii genome sequence reveals that this algae is also likely to synthesize sterols using a pathway resembling the higher plant pathway, indicating that its sterols are synthesized somewhat differently than in fungi. The work presented here seeks to establish experimental evidence to support the annotated molecular function of one of the sterol biosynthetic genes in the Chlamydomonas genome. Methodology/Principal Findings: A gene with homology to the yeast sterol C-5 desaturase, ERG3, is present in the Chlamydomonas genome. To test whether the ERG3 ortholog of C. reinhardtii encodes a sterol C-5 desaturase, Saccharomyces cerevisiae ERG3 knockout strains were created and