title: Membrane-bound lytic endotransglycosylase in Escherichia coli.
abstract: The gene for a novel endotype membrane-bound lytic transglycosylase, emtA, was mapped at 26.7 min of the E. coli chromosome. EmtA is a lipoprotein with an apparent molecular mass of 22kDa. Overexpression of the emtA gene did not result in bacteriolysis in vivo, but the enzyme was shown to hydrolyze glycan strands isolated from murein by amidase treatment. The formation of tetra- and hexasaccharides, but no disaccharides, reflects the endospecificity of the enzyme. The products are characterized by the presence of 1,6-anhydromuramic acid, indicating a lytic transglycosylase reaction mechanism. EmtA may function as a formatting enzyme that trims the nascent murein strands produced by the murein synthesis machinery into proper sizes, or it may be involved in the formation of tightly controlled minor holes in the murein sacculus to facilitate the export of bulky compounds across the murein barrier.
authors.affiliation: Abteilung Biochemie, Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
authors.forename: A R
authors.initials: AR
authors.lastname: Kraft
authors.forename: M F
authors.initials: MF
authors.lastname: Templin
authors.forename: J V
authors.initials: JV
authors.lastname: Höltje
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002462:Cell Membrane / Q000201:enzymology; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D016384:Consensus Sequence; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D005798:Genes, Bacterial; D016695:Glycosyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008074:Lipoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000378:metabolism; D019308:Palmitic Acid / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid
chemical_list: D008074:Lipoproteins; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D019308:Palmitic Acid; D016695:Glycosyltransferases; C021815:murein transglycosylase; D009238:N-Acetylmuramoyl-L-alanine Amidase