A Single Point Mutation in Mitochondrial Hsp70 Cochaperone Mge1 Gains Thermal Stability and Resistance
| Autor: | Srinivasu Karri, Lalitha Guruprasad, Adinarayana Marada, Yerranna Boggula, Praveen Kumar Allu, Swati Singh, Thanuja Krishnamoorthy, Naresh Babu V. Sepuri |
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| Rok vydání: | 2016 |
| Předmět: |
Models
Molecular 0301 basic medicine Protein Denaturation Protein Folding Circular dichroism Hot Temperature Saccharomyces cerevisiae Proteins Proteolysis Mutant Biology medicine.disease_cause Mitochondrial Membrane Transport Proteins Biochemistry Mitochondrial Proteins Nucleotide exchange factor 03 medical and health sciences Protein Domains medicine Point Mutation HSP70 Heat-Shock Proteins Thermal stability Amino Acid Sequence Escherichia coli Protein Unfolding Sequence Homology Amino Acid medicine.diagnostic_test Protein Stability Circular Dichroism Point mutation Yeast 030104 developmental biology Protein Multimerization Molecular Chaperones |
| Zdroj: | Biochemistry. 55:7065-7072 |
| ISSN: | 1520-4995 0006-2960 |
| Popis: | Mge1, a yeast homologue of Escherichia coli GrpE, is an evolutionarily conserved homodimeric nucleotide exchange factor of mitochondrial Hsp70. Temperature-dependent reversible structural alteration from a dimeric to a monomeric form is critical for Mge1 to act as a thermosensor. However, very limited information about the structural component or amino acid residue(s) that contributes to thermal sensing of Mge1/GrpE is available. In this report, we have identified a single point mutation, His167 to Leu (H167L), within the hinge region of Mge1 that confers thermal resistance to yeast. Circular dichroism, cross-linking, and refolding studies with recombinant proteins show that the Mge1 H167L mutant has increased thermal stability compared to that of wild-type Mge1 and also augments Hsp70-mediated protein refolding activity. While thermal denaturation studies suggest flexibility in the mutant, ionic quenching studies and limited proteolysis analysis reveal a relatively more rigid structure compared to that of the wild type. Intriguingly, Thermus thermophilus GrpE has a leucine at the corresponding position akin to the Mge1 mutant, and thermophilus proteins are well-known for their rigidity and hydrophobicity. Taken together, our results show that the yeast Mge1 H167L mutant functionally and structurally mimics T. thermophilus GrpE. |
| Databáze: | OpenAIRE |
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