title: Dynamic Organization of SecA and SecY Secretion Complexes in the B. subtilis Membrane.
abstract: In prokaryotes, about one third of cellular proteins are translocated across the plasma membrane or inserted into it by concerted action of the cytoplasmic ATPase SecA and the universally conserved SecYEG heterotrimeric polypeptide-translocating pore. Secretion complexes have been reported to localize in specific subcellular sites in Bacillus subtilis. In this work, we used a combination of total internal reflection microscopy, scanning fluorescence correlation spectroscopy, and pair correlation function to study the localization and dynamics of SecA and SecY in growing Bacillus subtilis cells. Both SecA and SecY localized in transient and dynamic foci in the cytoplasmic membrane, which displayed no higher-level organization in helices. Foci of SecA and SecY were in constant flux with freely diffusing SecA and SecY molecules. Scanning FCS confirmed the existence of populations of cellular SecA and SecY molecules with a wide range of diffusion coefficients. Diffusion of SecY as an uncomplexed molecular species was short-lived and only local while SecY complexed with its protein partners traversed distances of over half a micrometer in the cell.
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
authors.forename: Alex
authors.initials: A
authors.lastname: Dajkovic
authors.affiliation: School of Medical Sciences, University of New South Wales, Sydney, Australia 2052.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Hinde
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
authors.forename: Calum
authors.initials: C
authors.lastname: MacKichan
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
authors.forename: Rut
authors.initials: R
authors.lastname: Carballido-Lopez
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D000069816:SEC Translocation Channels / Q000378:metabolism*; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins