title: The transmembrane domain of N -acetylglucosaminyltransferase I is the key determinant for its Golgi subcompartmentation.
abstract: Golgi-resident type-II membrane proteins are asymmetrically distributed across the Golgi stack. The intrinsic features of the protein that determine its subcompartment-specific concentration are still largely unknown. Here, we used a series of chimeric proteins to investigate the contribution of the cytoplasmic, transmembrane and stem region of Nicotiana benthamiana N-acetylglucosaminyltransferase I (GnTI) for its cis/medial-Golgi localization and for protein-protein interaction in the Golgi. The individual GnTI protein domains were replaced with those from the well-known trans-Golgi enzyme α2,6-sialyltransferase (ST) and transiently expressed in Nicotiana benthamiana. Using co-localization analysis and N-glycan profiling, we show that the transmembrane domain of GnTI is the major determinant for its cis/medial-Golgi localization. By contrast, the stem region of GnTI contributes predominately to homomeric and heteromeric protein complex formation. Importantly, in transgenic Arabidopsis thaliana, a chimeric GnTI variant with altered sub-Golgi localization was not able to complement the GnTI-dependent glycosylation defect. Our results suggest that sequence-specific features in the transmembrane domain of GnTI account for its steady-state distribution in the cis/medial-Golgi in plants, which is a prerequisite for efficient N-glycan processing in vivo.
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, 1190, Austria.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Schoberer
authors.forename: Eva
authors.initials: E
authors.lastname: Liebminger
authors.forename: Ulrike
authors.initials: U
authors.lastname: Vavra
authors.forename: Christiane
authors.initials: C
authors.lastname: Veit
authors.forename: Alexandra
authors.initials: A
authors.lastname: Castilho
authors.forename: Martina
authors.initials: M
authors.lastname: Dicker
authors.forename: Daniel
authors.initials: D
authors.lastname: Maresch
authors.forename: Friedrich
authors.initials: F
authors.lastname: Altmann
authors.forename: Chris
authors.initials: C
authors.lastname: Hawes
authors.forename: Stanley W
authors.initials: SW
authors.lastname: Botchway
authors.forename: Richard
authors.initials: R
authors.lastname: Strasser
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D005816:Genetic Complementation Test; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism*; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D060066:Protein Interaction Maps; D017434:Protein Structure, Tertiary; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000166:cytology / Q000378:metabolism*; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
chemical_list: D010940:Plant Proteins; D011134:Polysaccharides; D011994:Recombinant Proteins; D017351:N-Acetylglucosaminyltransferases; D012799:Sialyltransferases; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
keywords: Arabidopsis thaliana; Golgi apparatus; N-glycan processing; Nicotiana benthamiana; glycosyltransferase; protein-protein interaction; transmembrane domain; type-II membrane protein