An osmotic-remedial, temperature-sensitive mutation in the allosteric activity site of ribonucleotide reductase in Neurospora crassa
| Autor: | David J. Jacobson, Myron L. Smith, N. L. Glass, S. P. Hubbard, O. C. Micali |
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| Rok vydání: | 2000 |
| Předmět: |
Osmosis
Genetic Linkage Protein subunit Genes Fungal Molecular Sequence Data Mutant Allosteric regulation Neurospora Neurospora crassa Catalytic Domain Ribonucleotide Reductases Genetics Animals Humans Amino Acid Sequence DNA Fungal Molecular Biology DNA Primers Base Sequence Sequence Homology Amino Acid biology Point mutation Genetic Complementation Test Temperature Crassa Chromosome Mapping biology.organism_classification Ribonucleotide reductase Biochemistry Mutation Allosteric Site Polymorphism Restriction Fragment Length |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 1432-1874 0026-8925 |
| DOI: | 10.1007/pl00008645 |
| Popis: | An osmotic-remedial, temperature-sensitive conditional mutant (un-24) was generated by Repeat Induced Point mutation (RIP) from a cross between a wild-type N. crassa strain and a strain carrying a approximately 250-kb duplication of the left arm of linkage group II (LGII). The mutation was mapped to the duplicated segment, within 2.6 map units of the heterokaryon incompatibility locus het-6. DNA transformation identified a 3.75-kb fragment that complemented the temperature-sensitive phenotype. A large ORF within this fragment was found to have a high degree of sequence identity to the large subunit of ribonucleotide reductase (RNR) from diverse organisms. Conserved amino acids at the active site and the allosteric activity sites are also evident. An unusual feature of the Neurospora sequence is a large insertion near the C-terminus relative to otherwise homologous sequences from other organisms. Three transition mutations, indicative of RIP, were identified in the N-terminal region of the temperature-sensitive mutant allele. One of these mutations results in a non-conservative amino acid substitution within the four-helix bundle that is important in the allosteric control of ribonucleotide reductase activity. This substitution appears to disrupt proper folding of the allosteric activity site during synthesis of the protein. |
| Databáze: | OpenAIRE |
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