title: Structures formed by a cell membrane-associated arabinogalactan-protein on graphite or mica alone and with Yariv phenylglycosides.
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).
  
  
  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.affiliation: 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.
authors.forename: Li Hong
authors.initials: LH
authors.lastname: Zhou
authors.affiliation: 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.
authors.forename: Renate A
authors.initials: RA
authors.lastname: Weizbauer
authors.affiliation: Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Singamaneni
authors.affiliation: Biomedical Engineering & Biomechanics Center, Xi'an Jiaotong University, Xi'an, China School of Life Science & Technology, Xi'an Jiaotong University, Xi'an, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.affiliation: Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA.
authors.forename: Guy M
authors.initials: GM
authors.lastname: Genin
authors.affiliation: Gladys Levis Allen Laboratory of Plant Sensory Physiology, Biology Department, Washington University in St. Louis, St. Louis, MO, USA pickard@wustl.edu.
authors.forename: Barbara G
authors.initials: BG
authors.lastname: Pickard
mesh_terms: D000538:Aluminum Silicates / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism / Q000648:ultrastructure*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure*; D005685:Galactans / Q000378:metabolism / Q000648:ultrastructure*; D017930:Genes, Reporter; D005960:Glucosides; D006108:Graphite / Q000378:metabolism*; D009088:Mucoproteins / Q000378:metabolism / Q000648:ultrastructure*; D058608:Nanopores; D010696:Phloroglucinol / Q000031:analogs & derivatives; D010940:Plant Proteins / Q000378:metabolism / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins
chemical_list: D000538:Aluminum Silicates; D005685:Galactans; D005960:Glucosides; D009088:Mucoproteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C104977:Yariv reagent; C006619:arabinogalactan proteins; D006108:Graphite; D010696:Phloroglucinol; C005653:arabinogalactan; C011934:mica
keywords: Arabidopsis thaliana; EGFP; LeAGP1; Plant cell walls; Yariv phenylglycoside; atomic force microscopy; glycoprotein cluster; glycoprotein mesh; lysine-rich arabinogalactan-protein; nanopore; periplasm