title: Golgi traffic and integrity depend on N-myristoyl transferase-1 in Arabidopsis.
abstract: N-myristoylation is a crucial irreversible eukaryotic lipid modification allowing a key subset of proteins to be targeted at the periphery of specific membrane compartments. Eukaryotes have conserved N-myristoylation enzymes, involving one or two N-myristoyltransferases (NMT1 and NMT2), among which NMT1 is the major enzyme. In the postembryonic developmental stages, defects in NMT1 lead to aberrant cell polarity, flower differentiation, fruit maturation, and innate immunity; however, no specific NMT1 target responsible for such deficiencies has hitherto been identified. Using a confocal microscopy forward genetics screen for the identification of Arabidopsis thaliana secretory mutants, we isolated STINGY, a recessive mutant with defective Golgi traffic and integrity. We mapped STINGY to a substitution at position 160 of Arabidopsis NMT1 (NMT1A160T). In vitro kinetic studies with purified NMT1A160T enzyme revealed a significant reduction in its activity due to a remarkable decrease in affinity for both myristoyl-CoA and peptide substrates. We show here that this recessive mutation is responsible for the alteration of Golgi traffic and integrity by predominantly affecting the Golgi membrane/cytosol partitioning of ADP-ribosylation factor proteins. Our results provide important functional insight into N-myristoylation in plants by ascribing postembryonic functions of Arabidopsis NMT1 that involve regulation of the functional and morphological integrity of the plant endomembranes.
authors.affiliation: Michigan State University-Department of Energy Plant Research Lab, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Luciana
authors.initials: L
authors.lastname: Renna
authors.forename: Giovanni
authors.initials: G
authors.lastname: Stefano
authors.forename: Wojciech
authors.initials: W
authors.lastname: Majeran
authors.forename: Chiara
authors.initials: C
authors.lastname: Micalella
authors.forename: Thierry
authors.initials: T
authors.lastname: Meinnel
authors.forename: Carmela
authors.initials: C
authors.lastname: Giglione
authors.forename: Federica
authors.initials: F
authors.lastname: Brandizzi
mesh_terms: D000214:Acyl Coenzyme A / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000235:genetics; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D005638:Fruit / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D015151:Immunoblotting; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D040901:Proteomics / Q000379:methods; D017386:Sequence Homology, Amino Acid
chemical_list: D000214:Acyl Coenzyme A; D029681:Arabidopsis Proteins; C040349:S-tetradecanoyl-coenzyme A; D008780:Methyltransferases; C419648:at3g18000 protein, Arabidopsis