Impact of single-residue mutations on protein thermal stability: The case of threonine 83 of BC2L-CN lectin.
Int J Biol Macromol
; 272(Pt 1): 132682, 2024 Jun.
Article
in En
| MEDLINE
| ID: mdl-38815947
ABSTRACT
The thermal stability of trimeric lectin BC2L-CN was investigated and found to be considerably altered when mutating residue 83, originally a threonine, located at the fucose-binding loop. Mutants were analyzed using differential scanning calorimetry and isothermal microcalorimetry. Although most mutations decreased the affinity of the protein for oligosaccharide H type 1, six mutations increased the melting temperature (Tm) by >5 °C; one mutation, T83P, increased the Tm value by 18.2 °C(T83P, Tm = 96.3 °C). In molecular dynamic simulations, the investigated thermostable mutants, T83P, T83A, and T83S, had decreased fluctuations in the loop containing residue 83. In the T83S mutation, the side-chain hydroxyl group of serine formed a hydrogen bond with a nearby residue, suggesting that the restricted movement of the side-chain resulted in fewer fluctuations and enhanced thermal stability. Residue 83 is located at the interface and near the upstream end of the equivalent loop in a different protomer; therefore, fluctuations by this residue likely propagate throughout the loop. Our study of the dramatic change in thermal stability by a single amino acid mutation provides useful insights into the rational design of protein structures, especially the structures of oligomeric proteins.
Key words
Full text:
1
Database:
MEDLINE
Main subject:
Threonine
/
Protein Stability
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Molecular Dynamics Simulation
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Mutation
Language:
En
Year:
2024
Type:
Article