Molecular Approaches to Probe Differential NADH Activation of Phosphoribulokinase Isozymes fromRhodobacter sphaeroides
| Autor: | Novak Js, F R Tabita |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Recombinant Fusion Proteins
Molecular Sequence Data Allosteric regulation Biophysics Rhodobacter sphaeroides Bacillus subtilis Biochemistry Isozyme Adenosine Triphosphate Amino Acid Sequence Molecular Biology Chromatography High Pressure Liquid Expression vector Sequence Homology Amino Acid Phosphoribulokinase Molecular mass biology NAD equipment and supplies biology.organism_classification eye diseases Enzyme Activation Isoenzymes Molecular Weight Phosphotransferases (Alcohol Group Acceptor) Chromatography Gel Mutagenesis Site-Directed Electrophoresis Polyacrylamide Gel sense organs Homologous recombination |
| Zdroj: | Archives of Biochemistry and Biophysics. 363:273-282 |
| ISSN: | 0003-9861 |
| DOI: | 10.1006/abbi.1998.1084 |
| Popis: | The cbbP I and cbbP II genes from Rhodobacter sphaeroides, encoding highly similar phosphoribulokinase (PRK) isozymes, PRK I and PRK II, respectively, exhibited differential allosteric activation by NADH. The two cbbP genes were cloned into expression vectors and homogeneous recombinant protein prepared. PRK II was found to be inherently less stable than PRK I; however, the addition of substrate ATP resulted in the complete protection of both isozymes to a 15-min incubation at 50°C. The relative molecular masses for both octameric isozymes were determined to be approximately 230,000; however, the protective effect of ATP was in accordance with aggregation of monomers to a molecular mass of approximately 750,000. While PRK I exhibited a nearly absolute dependence upon NADH for activity, PRK II retained substantial activity in the absence of NADH. PRK chimeras were thus constructed to facilitate elucidation of the basis for the differential effect of NADH, with advantage taken of the relative sequence identity of about 90% between the two isozymes. Chimeras were constructed either by in vivo homologous recombination, using the sacB gene from Bacillus subtilis as a conditionally lethal marker, or by using convenient restriction sites to combine different parts of the two cbbP genes. The PRK chimeras generated contained either the amino-terminal domain of PRK II and the carboxy-terminal domain of PRK I or the opposite configuration. Subsequent analyses of the chimeras pointed to particular regions and residue(s) as likely being important for NADH activation. |
| Databáze: | OpenAIRE |
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