title: Fluorescence correlation spectroscopy measurements of the membrane protein TetA in Escherichia coli suggest rapid diffusion at short length scales.
abstract: Structural inhomogeneities in biomembranes can lead to complex diffusive behavior of membrane proteins that depend on the length or time scales that are probed. This effect is well studied in eukaryotic cells, but has been explored only recently in bacteria. Here we used fluorescence recovery after photobleaching (FRAP) and fluorescence correlation spectroscopy (FCS) to study diffusion of the membrane protein TetA-YFP in E. coli. We find that the diffusion constant determined from FRAP is comparable to other reports of inner membrane protein diffusion constants in E. coli. However, FCS, which probes diffusion on shorter length scales, gives a value that is almost two orders of magnitude higher and is comparable to lipid diffusion constants. These results suggest there is a population of TetA-YFP molecules in the membrane that move rapidly over short length scales (~ 400 nm) but move significantly more slowly over the longer length scales probed by FRAP.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Chow
authors.forename: Lin
authors.initials: L
authors.lastname: Guo
authors.forename: Feng
authors.initials: F
authors.lastname: Gai
authors.forename: Mark
authors.initials: M
authors.lastname: Goulian
mesh_terms: D000465:Algorithms; D017920:Antiporters / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004058:Diffusion; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching / Q000379:methods; D007700:Kinetics; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013997:Time Factors
chemical_list: D017920:Antiporters; D001426:Bacterial Proteins; D008164:Luminescent Proteins; C079051:tetA protein, Bacteria; C054562:yellow fluorescent protein, Bacteria