title: Remodeling of membrane lipids in iron-starved Chlamydomonas.
abstract: Chlamydomonas reinhardtii cells exposed to abiotic stresses (e.g. nitrogen, zinc, or phosphorus deficiency) accumulate triacylglycerols (TAG), which are stored in lipid droplets. Here, we report that iron starvation leads to formation of lipid droplets and accumulation of TAGs. This occurs between 12 and 24 h after the switch to iron-starvation medium. C. reinhardtii cells deprived of iron have more saturated fatty acid (FA), possibly due to the loss of function of FA desaturases, which are iron-requiring enzymes with diiron centers. The abundance of a plastid acyl-ACP desaturase (FAB2) is decreased to the same degree as ferredoxin. Ferredoxin is a substrate of the desaturases and has been previously shown to be a major target of the iron deficiency response. The increase in saturated FA (C16:0 and C18:0) is concomitant with the decrease in unsaturated FA (C16:4, C18:3, or C18:4). This change was gradual for diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) and digalactosyldiacylglycerol (DGDG), whereas the monogalactosyldiacylglycerol (MGDG) FA profile remained stable during the first 12 h, whereas MGDG levels were decreasing over the same period of time. These changes were detectable after only 2 h of iron starvation. On the other hand, DGTS and DGDG contents gradually decreased until a minimum was reached after 24-48 h. RNA-Seq analysis of iron-starved C. reinhardtii cells revealed notable changes in many transcripts coding for enzymes involved in FA metabolism. The mRNA abundances of genes coding for components involved in TAG accumulation (diacylglycerol acyltransferases or major lipid droplet protein) were increased. A more dramatic increase at the transcript level has been observed for many lipases, suggesting that major remodeling of lipid membranes occurs during iron starvation in C. reinhardtii.
authors: From the Department of Chemistry and Biochemistry,. Electronic address: eugen.urzica@uni-muenster.de.
authors: Eugen I
authors: EI
authors: Urzica
authors: the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824.
authors: Astrid
authors: A
authors: Vieler
authors: From the Department of Chemistry and Biochemistry.
authors: Anne
authors: A
authors: Hong-Hermesdorf
authors: From the Department of Chemistry and Biochemistry.
authors: M Dudley
authors: MD
authors: Page
authors: the Institute of Genomics and Proteomics, and; the Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California 90095 and.
authors: David
authors: D
authors: Casero
authors: From the Department of Chemistry and Biochemistry.
authors: Sean D
authors: SD
authors: Gallaher
authors: From the Department of Chemistry and Biochemistry.
authors: Janette
authors: J
authors: Kropat
authors: the Institute of Genomics and Proteomics, and; the Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California 90095 and.
authors: Matteo
authors: M
authors: Pellegrini
authors: the Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824.
authors: Christoph
authors: C
authors: Benning
authors: From the Department of Chemistry and Biochemistry,; the Institute of Genomics and Proteomics, and; the Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California 90095 and. Electronic address: sabeeha@chem.ucla.edu.
authors: Sabeeha S
authors: SS
authors: Merchant
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D060365:Chloroplast Proteins / Q000378:metabolism; D051048:Diacylglycerol O-Acyltransferase / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D008049:Lipase / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D013997:Time Factors
chemical_list: D060365:Chloroplast Proteins; D008563:Membrane Lipids; D007501:Iron; D044943:Fatty Acid Desaturases; D051048:Diacylglycerol O-Acyltransferase; D008049:Lipase
keywords: Algae; Fatty Acid Desaturase; Iron; Lipid Metabolism; Plant Biochemistry; Triacylglycerol
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