The transmembrane domain of N –acetylglucosaminyltransferase I is the key determinant for its Golgi subcompartmentation. (21st October 2014)

• Record Type: Journal Article
• Authors: Schoberer, Jennifer; Liebminger, Eva; Vavra, Ulrike; Veit, Christiane; Castilho, Alexandra; Dicker, Martina; Maresch, Daniel; Altmann, Friedrich; Hawes, Chris; Botchway, Stanley W.; Strasser, Richard
• Is Part Of: Plant journal. Volume 80:Number 5(2014:Dec.)
• Page Start: 809
• Page End: 822
• Publication Date: 2014-10-21
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12671
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12671-abs-0001"> <title>Summary</title> <p>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 <italic>Nicotiana benthamiana N</italic>–acetylglucosaminyltransferase I (GnTI) for its <italic>cis</italic>/medial‐Golgi localization and for protein–protein interaction in the Golgi. The individual GnTI protein domains were replaced with those from the well‐known <italic>trans</italic>‐Golgi enzyme α2, 6–sialyltransferase (ST) and transiently expressed in <italic>Nicotiana benthamiana</italic>. Using co‐localization analysis and <italic>N</italic>–glycan profiling, we show that the transmembrane domain of GnTI is the major determinant for its <italic>cis</italic>/medial‐Golgi localization. By contrast, the stem region of GnTI contributes predominately to homomeric and heteromeric protein complex formation. Importantly, in transgenic <italic>Arabidopsis thaliana</italic>, 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 <italic>cis</italic>/medial‐Golgi in plants, which is a prerequisite for efficient <italic>N</italic>–glycan processing <italic>in vivo</italic>.</p> </abstract>