title: Crystallization of the cytotoxic domain of a ribosome-inactivating colicin in complex with its immunity protein.
abstract: The complex between the ribonuclease domain of the ribosome-inactivating colicin E3 and its protein inhibitor, the cognate immunity Im3, has been crystallized and preliminary X-ray characterization has been performed. Single crystals of the 1:1 complex were grown from hanging-drop vapour-diffusion experiments using 2-propanol as a precipitant. The space group is P3(1)21 or P3(2)21, with unit-cell parameters a = b = 93.7, c = 76.2 A. When cryocooled, these crystals diffract to a resolution of 2.4 A. A search for suitable conventional heavy-atom derivatives was unsuccessful and so Im3 mutants containing engineered cysteine or methionine residues have been produced for mercury soaks and selenomethionine-labelling experiments, respectively.
authors.affiliation: School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, England.
authors.forename: S
authors.initials: S
authors.lastname: Carr
authors.forename: D
authors.initials: D
authors.lastname: Walker
authors.forename: R
authors.initials: R
authors.lastname: James
authors.forename: C
authors.initials: C
authors.lastname: Kleanthous
authors.forename: A M
authors.initials: AM
authors.lastname: Hemmings
mesh_terms: D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000633:toxicity; D001665:Binding Sites; D003087:Colicins / Q000737:chemistry* / Q000235:genetics; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins; D008628:Mercury / Q000737:chemistry; D008715:Methionine / Q000737:chemistry / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D012260:Ribonucleases / Q000737:chemistry; D012645:Selenomethionine / Q000737:chemistry; D012694:Serine / Q000737:chemistry / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D003087:Colicins; D029968:Escherichia coli Proteins; C488855:ceiC protein, E coli; C007104:colicin immunity proteins; D012694:Serine; D012645:Selenomethionine; D008715:Methionine; D012260:Ribonucleases; D008628:Mercury