title: Diffusion of anionic and neutral GFP derivatives through plasmodesmata in epidermal cells of Nicotiana benthamiana.
abstract: Plasmodesmata (Pd) are trans-wall membrane channels that permit cell-to-cell transport of metabolites and other small molecules, proteins, RNAs, and signaling molecules. The transport of cytoplasmic soluble macromolecules is a function of the electrochemical gradient between adjacent cells, the number of Pd per interface between adjacent cells, Stokes radius (R(S)), area of the cytoplasmic annulus, and channel length. The size of the largest molecule that can pass through Pd defines the Pd size exclusion limit. However, since the shape and size of a molecule determines its capacity to diffuse through pores or tubes, R(S) is a better measure. Relatively small changes in R(S) can cause large differences in the mobility of molecular probes, particularly if the pore size is close to that of the probe. In addition, as the dimensions of a macromolecule approach that of the channel, membrane charge effects may become important. We employed quantitative tools and molecular modeling to measure the apparent coefficient of conductivity of Pd, C(Pd), for the non-targeted transport of macromolecules. This method allowed us to examine the influence of protein charge and R(S) on C(Pd) in Nicotiana benthamiana. The C(Pd) of modified green fluorescent proteins (GFPs) of different sizes but with the same charge as native GFP and of a more negatively charged derivative were determined. We found that the C(Pd) of cytoplasmic soluble GFP and cytoplasmic forms of modified GFP were the most strongly correlated with R(S) and that the apparent aberrant increase in C(Pd) of a negatively charged GFP derivative was, at least in part, the result of the charge effect on R(S).
authors.affiliation: Department of Plant Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Dashevskaya
authors.forename: Ronen Benjamine
authors.initials: RB
authors.lastname: Kopito
authors.forename: Ran
authors.initials: R
authors.lastname: Friedman
authors.forename: Michael
authors.initials: M
authors.lastname: Elbaum
authors.forename: Bernard L
authors.initials: BL
authors.lastname: Epel
mesh_terms: D000838:Anions / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism*; D004058:Diffusion; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D018613:Microscopy, Confocal; D015335:Molecular Probes / Q000378:metabolism; D019441:Plant Epidermis / Q000378:metabolism*; D031425:Plasmodesmata / Q000378:metabolism*; D011487:Protein Conformation; D021381:Protein Transport; D014026:Nicotiana / Q000378:metabolism*
chemical_list: D000838:Anions; D015335:Molecular Probes; D049452:Green Fluorescent Proteins
references.citation: Kidney Int. 2006 Apr;69(8):1295-7
references.pmid: 16612411
references.citation: Nat Biotechnol. 1996 Oct;14(10):1246-51
references.pmid: 9631087
references.citation: Pharm Res. 2007 Mar;24(3):502-11
references.pmid: 17245654
references.citation: J Microsc. 2007 Jan;225(Pt 1):49-71
references.pmid: 17286695
references.citation: Plant Physiol. 2001 Apr;125(4):1802-12
references.pmid: 11299360
references.citation: Gene. 1998 Oct 9;221(1):35-43
references.pmid: 9852947
references.citation: Annu Rev Cell Dev Biol. 2000;16:393-421
references.pmid: 11031242
references.citation: Int Rev Cytol. 2004;235:93-164
references.pmid: 15219782
references.citation: Genes Dev. 2002 Jan 15;16(2):151-8
references.pmid: 11799058
references.citation: Cell. 1999 Jun 11;97(6):743-54
references.pmid: 10380926
references.citation: Protoplasma. 2008;232(3-4):143-52
references.pmid: 18767215
references.citation: Plant Cell. 1999 Mar;11(3):309-22
references.pmid: 10072393
references.citation: Plant Cell. 2002;14 Suppl:S303-25
references.pmid: 12045285
references.citation: Protoplasma. 2005 Apr;225(1-2):67-76
references.pmid: 15868214
references.citation: Biophys J. 1999 Jul;77(1):542-52
references.pmid: 10388779
references.citation: Arch Biochem Biophys. 1992 Aug 15;297(1):46-51
references.pmid: 1637182
references.citation: Plant Cell. 1995 Dec;7(12):2069-79
references.pmid: 8718620
references.citation: Planta. 1983 Mar;157(2):124-30
references.pmid: 24264065
references.citation: Nat Struct Biol. 2000 Nov;7 Suppl:957-9
references.pmid: 11103999
references.citation: Planta. 1987 Jun;171(2):145-57
references.pmid: 24227322
references.citation: Plant Cell. 2005 Jun;17(6):1788-800
references.pmid: 15879561
references.citation: Plant J. 2005 Jan;41(2):319-31
references.pmid: 15634207
references.citation: Biochem Biophys Res Commun. 1995 Dec 5;217(1):21-7
references.pmid: 8526912
references.citation: Plant Cell. 2002 Oct;14(10):2431-50
references.pmid: 12368496
references.citation: Micron. 2000 Dec;31(6):713-21
references.pmid: 10838030
references.citation: Am J Physiol Renal Physiol. 2001 Oct;281(4):F579-96
references.pmid: 11553505
references.citation: Proc Natl Acad Sci U S A. 2007 Jul 31;104(31):12743-8
references.pmid: 17646647
references.citation: Biophys J. 1997 Jan;72(1):204-13
references.pmid: 8994605
references.citation: Am J Physiol Renal Physiol. 2006 Nov;291(5):F1083-9
references.pmid: 16735459
references.citation: Am J Physiol Renal Physiol. 2005 Apr;288(4):F605-13
references.pmid: 15753324
references.citation: Proteins. 1997 Oct;29(2):240-51
references.pmid: 9329088
references.citation: J Chromatogr A. 2004 Apr 30;1035(1):83-6
references.pmid: 15117077
references.citation: Plant Cell. 1997 Jul;9(7):1043-54
references.pmid: 9254930
references.citation: Anal Biochem. 2007 Sep 1;368(1):95-9
references.pmid: 17586454
references.citation: Planta. 2002 May;215(1):67-78
references.pmid: 12012243