title: Crystal structure of the biologically active form of class Ib ribonucleotide reductase small subunit from Mycobacterium tuberculosis.
abstract: Two nrdF genes of Mycobacterium tuberculosis code for different R2 subunits of the class Ib ribonucleotide reductase (RNR). The proteins are denoted R2F-1 and R2F-2 having 71% sequence identity. The R2F-2 subunit forms the biologically active RNR complex with the catalytic R1E-subunit. We present the structure of the reduced R2F-2 subunit to 2.2 A resolution. Comparison of the R2F-2 structure with a model of R2F-1 suggests that the important differences are located at the C-terminus. We found that within class Ib, the E-helix close to the iron diiron centre has two preferred conformations, which cannot be explained by the redox-state of the diiron centre. In the R2F-2 structure, we also could see a mobility of alphaE in between the two conformations.
authors.affiliation: Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala Biomedical Center, P.O. Box 590, SE-751 24 Uppsala, Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Uppsten
authors.forename: Jamaine
authors.initials: J
authors.lastname: Davis
authors.forename: Harvey
authors.initials: H
authors.lastname: Rubin
authors.forename: Ulla
authors.initials: U
authors.lastname: Uhlin
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray / Q000379:methods; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D012264:Ribonucleotide Reductases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D021122:Protein Subunits; C114872:NrdF protein, bacteria; D012264:Ribonucleotide Reductases