title: Premature targeting of cell division proteins to midcell reveals hierarchies of protein interactions involved in divisome assembly.
abstract: In order to divide, the bacterium Escherichia coli must assemble a set of at least 10 essential proteins at the nascent division site. These proteins localize to midcell according to a linear hierarchy, suggesting that cell division proteins are added to the nascent divisome in strict sequence. We previously described a method, 'premature targeting', which allows us to target a protein directly to the division site independently of other cell division proteins normally required for its localization at midcell. By systematically applying this method to probe the recruitment of and associations among late cell division proteins, we show that this linear assembly model is likely incorrect. Rather, we find that the assembly of most of the late proteins can occur independently of 'upstream' proteins. Further, most late proteins, when prematurely targeted to midcell, can back-recruit upstream proteins in the reverse of the predicted pathway. Together these observations indicate that the late proteins, with the notable exception of the last protein in the pathway, FtsN, are associated in a hierarchical set of protein complexes. Based on these observations we present a revised model for assembly of the E. coli division apparatus.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Goehring
authors.forename: Mark D
authors.initials: MD
authors.lastname: Gonzalez
authors.forename: Jon
authors.initials: J
authors.lastname: Beckwith
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D046915:Penicillin-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D046928:Peptidoglycan Glycosyltransferase / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D029968:Escherichia coli Proteins; C456028:FtsB protein, E coli; C478704:FtsI protein, E coli; C068023:FtsQ protein, E coli; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D046915:Penicillin-Binding Proteins; D011993:Recombinant Fusion Proteins; C078387:ftsL protein, E coli; C061684:FtsW protein, Bacteria; D046928:Peptidoglycan Glycosyltransferase