title: Diversity in Overall Activity Regulation of Ribonucleotide Reductase.
abstract: Ribonucleotide reductase (RNR) catalyzes the reduction of ribonucleotides to the corresponding deoxyribonucleotides, which are used as building blocks for DNA replication and repair. This process is tightly regulated via two allosteric sites, the specificity site (s-site) and the overall activity site (a-site). The a-site resides in an N-terminal ATP cone domain that binds dATP or ATP and functions as an on/off switch, whereas the composite s-site binds ATP, dATP, dTTP, or dGTP and determines which substrate to reduce. There are three classes of RNRs, and class I RNRs consist of different combinations of α and β subunits. In eukaryotic and Escherichia coli class I RNRs, dATP inhibits enzyme activity through the formation of inactive α6 and α4β4 complexes, respectively. Here we show that the Pseudomonas aeruginosa class I RNR has a duplicated ATP cone domain and represents a third mechanism of overall activity regulation. Each α polypeptide binds three dATP molecules, and the N-terminal ATP cone is critical for binding two of the dATPs because a truncated protein lacking this cone could only bind dATP to its s-site. ATP activates the enzyme solely by preventing dATP from binding. The dATP-induced inactive form is an α4 complex, which can interact with β2 to form a non-productive α4β2 complex. Other allosteric effectors induce a mixture of α2 and α4 forms, with the former being able to interact with β2 to form active α2β2 complexes. The unique features of the P. aeruginosa RNR are interesting both from evolutionary and drug discovery perspectives.
authors.affiliation: From the Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå and.
authors.forename: Venkateswara Rao
authors.initials: VR
authors.lastname: Jonna
authors.affiliation: the Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Crona
authors.affiliation: From the Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå and.
authors.forename: Reza
authors.initials: R
authors.lastname: Rofougaran
authors.affiliation: the Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lundin
authors.affiliation: From the Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå and.
authors.forename: Samuel
authors.initials: S
authors.lastname: Johansson
authors.affiliation: From the Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå and.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Brännström
authors.affiliation: the Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Britt-Marie
authors.initials: BM
authors.lastname: Sjöberg
authors.affiliation: From the Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå and anders.hofer@medchem.umu.se.
authors.forename: Anders
authors.initials: A
authors.lastname: Hofer
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D000495:Allosteric Site; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003838:Deoxyadenine Nucleotides / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D021122:Protein Subunits; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics; D012264:Ribonucleotide Reductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion
chemical_list: D001426:Bacterial Proteins; D003838:Deoxyadenine Nucleotides; D029968:Escherichia coli Proteins; D021122:Protein Subunits; D000255:Adenosine Triphosphate; D012264:Ribonucleotide Reductases; C026600:2'-deoxyadenosine triphosphate
keywords: Pseudomonas aeruginosa (P. aeruginosa); allosteric regulation; dATP inhibition; enzyme inactivation; oligomerization; overall activity regulation; protein complex; ribonucleotide reductase