title: Arabidopsis ERG28 tethers the sterol C4-demethylation complex to prevent accumulation of a biosynthetic intermediate that interferes with polar auxin transport.
abstract: Sterols are vital for cellular functions and eukaryotic development because of their essential role as membrane constituents. Sterol biosynthetic intermediates (SBIs) represent a potential reservoir of signaling molecules in mammals and fungi, but little is known about their functions in plants. SBIs are derived from the sterol C4-demethylation enzyme complex that is tethered to the membrane by Ergosterol biosynthetic protein28 (ERG28). Here, using nonlethal loss-of-function strategies focused on Arabidopsis thaliana ERG28, we found that the previously undetected SBI 4-carboxy-4-methyl-24-methylenecycloartanol (CMMC) inhibits polar auxin transport (PAT), a key mechanism by which the phytohormone auxin regulates several aspects of plant growth, including development and responses to environmental factors. The induced accumulation of CMMC in Arabidopsis erg28 plants was associated with diagnostic hallmarks of altered PAT, including the differentiation of pin-like inflorescence, loss of apical dominance, leaf fusion, and reduced root growth. PAT inhibition by CMMC occurs in a brassinosteroid-independent manner. The data presented show that ERG28 is required for PAT in plants. Furthermore, it is accumulation of an atypical SBI that may act to negatively regulate PAT in plants. Hence, the sterol pathway offers further prospects for mining new target molecules that could regulate plant development.
authors: Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique and Université de Strasbourg, 67084 Strasbourg cedex, France.
authors: Alexis Samba
authors: AS
authors: Mialoundama
authors: Nurul
authors: N
authors: Jadid
authors: Julien
authors: J
authors: Brunel
authors: Thomas
authors: T
authors: Di Pascoli
authors: Dimitri
authors: D
authors: Heintz
authors: Mathieu
authors: M
authors: Erhardt
authors: Jérôme
authors: J
authors: Mutterer
authors: Marc
authors: M
authors: Bergdoll
authors: Daniel
authors: D
authors: Ayoub
authors: Alain
authors: A
authors: Van Dorsselaer
authors: Alain
authors: A
authors: Rahier
authors: Paul
authors: P
authors: Nkeng
authors: Philippe
authors: P
authors: Geoffroy
authors: Michel
authors: M
authors: Miesch
authors: Bilal
authors: B
authors: Camara
authors: Florence
authors: F
authors: Bouvier
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001692:Biological Transport; D053898:Biosynthetic Pathways; D007210:Indoleacetic Acids / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010840:Phytosterols / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: C000592335:4-carboxy-4-methyl-24-methylenecycloartanol; D029681:Arabidopsis Proteins; C000592334:ERG28 protein, Arabidopsis; D007210:Indoleacetic Acids; D008565:Membrane Proteins; D010840:Phytosterols