Single-Molecule Motions of Oligoarginine Transporter Conjugates on the Plasma Membrane of Chinese Hamster Ovary Cells

@article{citeulike:2931894, abstract = {Abstract: To explore the real-time dynamic behavior of molecular transporters of the cell-penetrating-peptide (CPP) type on a biological membrane, single fluorescently labeled oligoarginine conjugates were imaged interacting with the plasma membrane of Chinese hamster ovary (CHO) cells. The diffusional motion on the membrane, characterized by single-molecule diffusion coefficient and residence time (\"{A}R), defined as the time from the initial appearance of a single-molecule spot on the membrane (from the solution) to the time the single molecule disappears from the imaging focal plane, was observed for a fluorophore-labeled octaarginine (a model guanidinium-rich CPP) and compared with the corresponding values observed for a tetraarginine conjugate (negative control), a lipid analogue, and a fluorescently labeled protein conjugate (transferrin-Alexa594) known to enter the cell through endocytosis. Imaging of the oligoarginine conjugates was enabled by the use of a new high-contrast fluorophore in the dicyanomethylenedihydrofuran family, which brightens upon interaction with the membrane at normal oxygen concentrations. Taken as a whole, the motions of the octaarginine conjugate single molecules are highly heterogeneous and cannot be described as Brownian motion with a single diffusion coefficient. The observed behavior is also different from that of lipids, known to penetrate cellular membranes through passive diffusion, conventionally involving lateral diffusion followed by membrane bilayer flip-flop. Furthermore, while the octaarginine conjugate behavior shares some common features with transferrin uptake (endocytotic) processes, the two systems also exhibit dissimilar traits when diffusional motions and residence times of single constructs are compared. Additionally, pretreatment of cells with cytochalasin D, a known actin filament disruptor, produces no significant effect, which further rules out unimodal endocytosis as the mechanism of uptake. Also, the involvement of membrane potential in octaargininemembrane interaction is supported by significant changes in the motion with high [K+] treatment. In sum, this first study of single transporter motion on the membrane of a living cell indicates that the mode by which the octaarginine transporter penetrates the cell membrane appears to either be a multimechanism uptake process or a mechanism different from unimodal passive diffusion or endocytosis.}, address = {Department of Chemistry and Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, and Department of Chemistry, Kent State University, Kent, Ohio 44242}, author = {Lee, H. L. and Dubikovskaya, E. A. and Hwang, H. and Semyonov, A. N. and Wang, H. and Jones, L. R. and Twieg, R. J. and Moerner, W. E. and Wender, P. A. }, citeulike-article-id = {2931894}, doi = {10.1021/ja710798b}, journal = {J. Am. Chem. Soc.}, keywords = {biophysics, dcdhfs, sms}, month = {June}, posted-at = {2008-06-26 19:03:37}, priority = {2}, title = {Single-Molecule Motions of Oligoarginine Transporter Conjugates on the Plasma Membrane of Chinese Hamster Ovary Cells}, url = {http://dx.doi.org/10.1021/ja710798b}, year = {2008} }

TY - JOUR ID - citeulike:2931894 L3 - citeulike-article-id:2931894 TI - Single-Molecule Motions of Oligoarginine Transporter Conjugates on the Plasma Membrane of Chinese Hamster Ovary Cells JF - J. Am. Chem. Soc. AD - Department of Chemistry and Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, and Department of Chemistry, Kent State University, Kent, Ohio 44242 N2 - Abstract: To explore the real-time dynamic behavior of molecular transporters of the cell-penetrating-peptide (CPP) type on a biological membrane, single fluorescently labeled oligoarginine conjugates were imaged interacting with the plasma membrane of Chinese hamster ovary (CHO) cells. The diffusional motion on the membrane, characterized by single-molecule diffusion coefficient and residence time (ÄR), defined as the time from the initial appearance of a single-molecule spot on the membrane (from the solution) to the time the single molecule disappears from the imaging focal plane, was observed for a fluorophore-labeled octaarginine (a model guanidinium-rich CPP) and compared with the corresponding values observed for a tetraarginine conjugate (negative control), a lipid analogue, and a fluorescently labeled protein conjugate (transferrin-Alexa594) known to enter the cell through endocytosis. Imaging of the oligoarginine conjugates was enabled by the use of a new high-contrast fluorophore in the dicyanomethylenedihydrofuran family, which brightens upon interaction with the membrane at normal oxygen concentrations. Taken as a whole, the motions of the octaarginine conjugate single molecules are highly heterogeneous and cannot be described as Brownian motion with a single diffusion coefficient. The observed behavior is also different from that of lipids, known to penetrate cellular membranes through passive diffusion, conventionally involving lateral diffusion followed by membrane bilayer flip-flop. Furthermore, while the octaarginine conjugate behavior shares some common features with transferrin uptake (endocytotic) processes, the two systems also exhibit dissimilar traits when diffusional motions and residence times of single constructs are compared. Additionally, pretreatment of cells with cytochalasin D, a known actin filament disruptor, produces no significant effect, which further rules out unimodal endocytosis as the mechanism of uptake. Also, the involvement of membrane potential in octaargininemembrane interaction is supported by significant changes in the motion with high [K+] treatment. In sum, this first study of single transporter motion on the membrane of a living cell indicates that the mode by which the octaarginine transporter penetrates the cell membrane appears to either be a multimechanism uptake process or a mechanism different from unimodal passive diffusion or endocytosis. KW - biophysics KW - dcdhfs KW - sms AU - Lee, HL AU - Dubikovskaya, EA AU - Hwang, H AU - Semyonov, AN AU - Wang, H AU - Jones, LR AU - Twieg, RJ AU - Moerner, WE AU - Wender, PA PY - 2008/06/26/ UR - http://dx.doi.org/10.1021/ja710798b ER -