title: Intermediate states of ribonuclease III in complex with double-stranded RNA.
abstract: Bacterial ribonuclease III (RNase III) can affect RNA structure and gene expression in either of two ways: as a processing enzyme that cleaves double-stranded (ds) RNA, or as a binding protein that binds but does not cleave dsRNA. We previously proposed a model of the catalytic complex of RNase III with dsRNA based on three crystal structures, including the endonuclease domain of RNase III with and without bound metal ions and a dsRNA binding protein complexed with dsRNA. We also reported a noncatalytic assembly observed in the crystal structure of an RNase III mutant, which binds but does not cleave dsRNA, complexed with dsRNA. We hypothesize that the RNase III*dsRNA complex can exist in two functional forms, a catalytic complex and a noncatalytic assembly, and that in between the two forms there may be intermediate states. Here, we present four crystal structures of RNase III complexed with dsRNA, representing possible intermediates.
authors.affiliation: Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Gan
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Tropea
authors.forename: Brian P
authors.initials: BP
authors.lastname: Austin
authors.forename: Donald L
authors.initials: DL
authors.lastname: Court
authors.forename: David S
authors.initials: DS
authors.lastname: Waugh
authors.forename: Xinhua
authors.initials: X
authors.lastname: Ji
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D005583:Fourier Analysis; D008956:Models, Chemical; D008958:Models, Molecular; D009154:Mutation; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D021122:Protein Subunits; D012330:RNA, Double-Stranded / Q000737:chemistry / Q000378:metabolism*; D043244:Ribonuclease III / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013059:Spectrum Analysis, Raman; D013698:Templates, Genetic; D014961:X-Ray Diffraction
chemical_list: D021122:Protein Subunits; D012330:RNA, Double-Stranded; D043244:Ribonuclease III