FAX1, a Novel Membrane Protein Mediating Plastid Fatty Acid Export

Fatty acid synthesis in plants occurs in plastids, and thus, export for subsequent acyl editing and lipid assembly in the cytosol and endoplasmatic reticulum is required. Yet, the transport mechanism for plastid fatty acids still remains enigmatic. We isolated FAX1 (fatty acid export 1), a novel pro...

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Vydané v:	PLoS biology Ročník 13; číslo 2; s. e1002053
Hlavní autori:	Li, Nannan, Gügel, Irene Luise, Giavalisco, Patrick, Zeisler, Viktoria, Schreiber, Lukas, Soll, Jürgen, Philippar, Katrin
Médium:	Journal Article
Jazyk:	English
Vydavateľské údaje:	United States Public Library of Science 01.02.2015 Public Library of Science (PLoS)
Predmet:	Amino Acid Sequence Arabidopsis - genetics Arabidopsis - metabolism Arabidopsis Proteins - chemistry Arabidopsis Proteins - genetics Arabidopsis Proteins - metabolism Biodiesel fuels Biological Transport Chloroplasts Colleges & universities Deoxyribonucleic acid DNA Endoplasmic Reticulum - metabolism Fatty acids Fatty Acids - metabolism Fertility - genetics Flowers & plants Flowers - genetics Flowers - metabolism Gene expression Gene Expression Profiling Gene Expression Regulation, Plant Gene Knockout Techniques Genetic Complementation Test Genomes Glycerol Lipid Metabolism - genetics Lipids Membrane proteins Membrane Proteins - chemistry Membrane Proteins - genetics Membrane Proteins - metabolism Membranes Metabolism Models, Molecular Molecular Sequence Data NMR Nuclear magnetic resonance Physiological aspects Plant Leaves - genetics Plant Leaves - metabolism Plastids Plastids - metabolism Protein Structure, Secondary Protein Structure, Tertiary Proteins Recombinant Fusion Proteins - chemistry Recombinant Fusion Proteins - genetics Recombinant Fusion Proteins - metabolism Sequence Alignment Vertebrates Yeast
ISSN:	1545-7885, 1544-9173, 1545-7885
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Shrnutí:	Fatty acid synthesis in plants occurs in plastids, and thus, export for subsequent acyl editing and lipid assembly in the cytosol and endoplasmatic reticulum is required. Yet, the transport mechanism for plastid fatty acids still remains enigmatic. We isolated FAX1 (fatty acid export 1), a novel protein, which inserts into the chloroplast inner envelope by α-helical membrane-spanning domains. Detailed phenotypic and ultrastructural analyses of FAX1 mutants in Arabidopsis thaliana showed that FAX1 function is crucial for biomass production, male fertility and synthesis of fatty acid-derived compounds such as lipids, ketone waxes, or pollen cell wall material. Determination of lipid, fatty acid, and wax contents by mass spectrometry revealed that endoplasmatic reticulum (ER)-derived lipids decreased when FAX1 was missing, but levels of several plastid-produced species increased. FAX1 over-expressing lines showed the opposite behavior, including a pronounced increase of triacyglycerol oils in flowers and leaves. Furthermore, the cuticular layer of stems from fax1 knockout lines was specifically reduced in C29 ketone wax compounds. Differential gene expression in FAX1 mutants as determined by DNA microarray analysis confirmed phenotypes and metabolic imbalances. Since in yeast FAX1 could complement for fatty acid transport, we concluded that FAX1 mediates fatty acid export from plastids. In vertebrates, FAX1 relatives are structurally related, mitochondrial membrane proteins of so-far unknown function. Therefore, this protein family might represent a powerful tool not only to increase lipid/biofuel production in plants but also to explore novel transport systems involved in vertebrate fatty acid and lipid metabolism.
Bibliografia:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Conceived and designed the experiments: NL JS KP. Performed the experiments: NL ILG PG VZ LS. Analyzed the data: NL PG LS KP. Wrote the paper: NL PG LS KP. Performed structural modeling: KP. The authors have declared that no competing interests exist.
ISSN:	1545-7885 1544-9173 1545-7885
DOI:	10.1371/journal.pbio.1002053