Golgi-localized LOT regulates trans-Golgi network biogenesis and pollen tube growth

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 115; no. 48; pp. 12307 - 12312
• Main Authors: Jia, Peng-Fei, Xue, Yong, Li, Hong-Ju, Yang, Wei-Cai
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 27.11.2018
• Subjects: Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biological Sciences; Biosynthesis; Cells; Evolution; Extracellular matrix; Golgi apparatus; Golgi Apparatus - genetics; Golgi Apparatus - metabolism; Golgi Matrix Proteins - genetics; Golgi Matrix Proteins - metabolism; Guanine; Guanine nucleotide exchange factor; Guanine Nucleotide Exchange Factors - genetics; Guanine Nucleotide Exchange Factors - metabolism; Guanosine triphosphatases; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Kinases; Localization; Molecular biology; Mutation; Pectin; Pollen; Pollen Tube - genetics; Pollen Tube - growth & development; Pollen Tube - metabolism; Protein Transport; Proteins; trans-Golgi Network - genetics; trans-Golgi Network - metabolism; Yeast; Golgi; TGN biogenesis; pollen tube growth; vesicle trafficking
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1809206115

The trans-Golgi network (TGN) is an essential tubular-vesicular organelle derived from the Golgi and functions as an independent sorting and trafficking hub within the cell. However, the molecular regulation of TGN biogenesis remains enigmatic. Here we identified an Arabidopsis mutant loss of TGN (lot) that is defective in TGN formation and sterile due to impaired pollen tube growth in the style. The mutation leads to overstacking of the Golgi cisternae and significant reduction in the number of TGNs and vesicles surrounding the Golgi in pollen, which is corroborated by the dispersed cytosolic distribution of TGN-localized proteins. Consistently, deposition of extracellular pectin and plasma membrane localization of kinases and phosphoinositide species are also impaired. Subcellular localization analysis suggests that LOT is localized on the periphery of the Golgi cisternae, but the mutation does not affect the localization of Golgi-resident proteins. Furthermore, the yeast complementation result suggests that LOT could functionally act as a component of the guanine nucleotide exchange factor (GEF) complex of small Rab GTPase Ypt6. Taken together, these findings suggest that LOT is a critical player for TGN biogenesis in the plant lineage.