title: The FtsQ protein of Escherichia coli: membrane topology, abundance, and cell division phenotypes due to overproduction and insertion mutations.
abstract: The ftsQ gene is one of several genes thought to be specifically required for septum formation in Escherichia coli. Published work on the cell division behavior of ftsQ temperature-sensitive mutants suggested that the FtsQ product is required throughout the whole process of septum formation. Here we provide additional support for this hypothesis based on microscopic observations of the cell division defects resulting from insertional and temperature-sensitive mutations in the ftsQ gene, and constitutive overexpression of its gene product. On the basis of the published, predicted amino acid sequence of the FtsQ protein and our analysis of fusion proteins of the FtsQ protein to bacterial alkaline phosphatase, we conclude that FtsQ is a simple cytoplasmic membrane protein with a approximately 25-amino-acid cytoplasmic domain and a approximately 225-amino-acid periplasmic domain. We estimate that the FtsQ protein is present at about 22 copies per cell.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: M J
authors.initials: MJ
authors.lastname: Carson
authors.forename: J
authors.initials: J
authors.lastname: Barondess
authors.forename: J
authors.initials: J
authors.lastname: Beckwith
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002451:Cell Compartmentation; D002455:Cell Division; D002462:Cell Membrane / Q000648:ultrastructure; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004926:Escherichia coli / Q000502:physiology* / Q000648:ultrastructure; D029968:Escherichia coli Proteins; D015870:Gene Expression; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C068023:FtsQ protein, E coli; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins