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A Single Point Mutation in Mitochondrial Hsp70 Cochaperone Mge1 Gains Thermal Stability and Resistance
- Source :
- Biochemistry. 55:7065-7072
- Publication Year :
- 2016
- Publisher :
- American Chemical Society (ACS), 2016.
-
Abstract
- 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.
- Subjects :
- 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
Subjects
Details
- ISSN :
- 15204995 and 00062960
- Volume :
- 55
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....185b0251b04649b9f4ad7f93606158c8