title: Localization of the Escherichia coli cell division protein Ftsl (PBP3) to the division site and cell pole.
abstract: FtsI, also known as penicillin-binding protein 3, is a transpeptidase required for the synthesis of peptidoglycan in the division septum of the bacterium, Escherichia coli. FtsI has been estimated to be present at about 100 molecules per cell, well below the detection limit of immunoelectron microscopy. Here, we confirm the low abundance of FtsI and use immunofluorescence microscopy, a highly sensitive technique, to show that FtsI is localized to the division site during the later stages of cell growth. FtsI was also sometimes observed at the cell pole; polar localization was not anticipated and its significance is not known. We conclude (i) that immunofluorescence microscopy can be used to localize proteins whose abundance is as low as approximately 100 molecules per cell; and (ii) that spatial and temporal regulation of FtsI activity in septum formation is achieved, at least in part, by timed localization of the protein to the division site.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Weiss
authors.forename: K
authors.initials: K
authors.lastname: Pogliano
authors.forename: M
authors.initials: M
authors.lastname: Carson
authors.forename: L M
authors.initials: LM
authors.lastname: Guzman
authors.forename: C
authors.initials: C
authors.lastname: Fraipont
authors.forename: M
authors.initials: M
authors.lastname: Nguyen-Distèche
authors.forename: R
authors.initials: R
authors.lastname: Losick
authors.forename: J
authors.initials: J
authors.lastname: Beckwith
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000918:Antibody Specificity; D001426:Bacterial Proteins / Q000235:genetics; D015153:Blotting, Western; D002352:Carrier Proteins; D002455:Cell Division / Q000235:genetics; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D004926:Escherichia coli / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005838:Genotype; D006602:Hexosyltransferases / Q000276:immunology / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009097:Multienzyme Complexes / Q000276:immunology / Q000378:metabolism*; D002267:Muramoylpentapeptide Carboxypeptidase; D046915:Penicillin-Binding Proteins; D046928:Peptidoglycan Glycosyltransferase; D010458:Peptidyl Transferases / Q000276:immunology / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D029968:Escherichia coli Proteins; C478704:FtsI protein, E coli; C071525:FtsZ protein, Bacteria; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D046928:Peptidoglycan Glycosyltransferase; D000469:Alkaline Phosphatase; D002267:Muramoylpentapeptide Carboxypeptidase