Li Hong Zhou1, Renate A Weizbauer2, Srikanth Singamaneni3, Feng Xu4, Guy M Genin3, Barbara G Pickard5. 1. Gladys Levis Allen Laboratory of Plant Sensory Physiology, Biology Department, Washington University in St. Louis, St. Louis, MO, USA Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA Biomedical Engineering & Biomechanics Center, Xi'an Jiaotong University, Xi'an, China. 2. Gladys Levis Allen Laboratory of Plant Sensory Physiology, Biology Department, Washington University in St. Louis, St. Louis, MO, USA Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA Carnegie Institution, Department of Plant Biology, Stanford, CA, USA. 3. Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA. 4. Biomedical Engineering & Biomechanics Center, Xi'an Jiaotong University, Xi'an, China School of Life Science & Technology, Xi'an Jiaotong University, Xi'an, China. 5. Gladys Levis Allen Laboratory of Plant Sensory Physiology, Biology Department, Washington University in St. Louis, St. Louis, MO, USA pickard@wustl.edu.
Abstract
BACKGROUND: Certain membrane-associated arabinogalactan-proteins (AGPs) with lysine-rich sub-domains participate in plant growth, development and resistance to stress. To complement fluorescence imaging of such molecules when tagged and introduced transgenically to the cell periphery and to extend the groundwork for assessing molecular structure, some behaviours of surface-spread AGPs were visualized at the nanometre scale in a simplified electrostatic environment. METHODS: Enhanced green fluorescent protein (EGFP)-labelled LeAGP1 was isolated from Arabidopsis thaliana leaves using antibody-coated magnetic beads, deposited on graphite or mica, and examined with atomic force microscopy (AFM). KEY RESULTS: When deposited at low concentration on graphite, LeAGP can form independent clusters and rings a few nanometres in diameter, often defining deep pits; the aperture of the rings depends on plating parameters. On mica, intermediate and high concentrations, respectively, yielded lacy meshes and solid sheets that could dynamically evolve arcs, rings, 'pores' and 'co-pores', and pits. Glucosyl Yariv reagent combined with the AGP to make very large and distinctive rings. CONCLUSIONS: Diverse cell-specific nano-patterns of native lysine-rich AGPs are expected at the wall-membrane interface and, while there will not be an identical patterning in different environmental settings, AFM imaging suggests protein tendencies for surficial organization and thus opens new avenues for experimentation. Nanopore formation with Yariv reagents suggests how the reagent might bind with AGP to admit Ca(2+) to cells and hints at ways in which AGP might be structured at some cell surfaces.
BACKGROUND: Certain membrane-associated arabinogalactan-proteins (AGPs) with lysine-rich sub-domains participate in plant growth, development and resistance to stress. To complement fluorescence imaging of such molecules when tagged and introduced transgenically to the cell periphery and to extend the groundwork for assessing molecular structure, some behaviours of surface-spread AGPs were visualized at the nanometre scale in a simplified electrostatic environment. METHODS: Enhanced green fluorescent protein (EGFP)-labelled LeAGP1 was isolated from Arabidopsis thaliana leaves using antibody-coated magnetic beads, deposited on graphite or mica, and examined with atomic force microscopy (AFM). KEY RESULTS: When deposited at low concentration on graphite, LeAGP can form independent clusters and rings a few nanometres in diameter, often defining deep pits; the aperture of the rings depends on plating parameters. On mica, intermediate and high concentrations, respectively, yielded lacy meshes and solid sheets that could dynamically evolve arcs, rings, 'pores' and 'co-pores', and pits. Glucosyl Yariv reagent combined with the AGP to make very large and distinctive rings. CONCLUSIONS: Diverse cell-specific nano-patterns of native lysine-rich AGPs are expected at the wall-membrane interface and, while there will not be an identical patterning in different environmental settings, AFM imaging suggests protein tendencies for surficial organization and thus opens new avenues for experimentation. Nanopore formation with Yariv reagents suggests how the reagent might bind with AGP to admit Ca(2+) to cells and hints at ways in which AGP might be structured at some cell surfaces.
Authors: Marcus Kostka; Tobias Högen; Karin M Danzer; Johannes Levin; Matthias Habeck; Andreas Wirth; Richard Wagner; Charles G Glabe; Sabine Finger; Udo Heinzelmann; Patrick Garidel; Wenzhen Duan; Christopher A Ross; Hans Kretzschmar; Armin Giese Journal: J Biol Chem Date: 2008-02-07 Impact factor: 5.157