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Investigating the effects of double mutation C30A/C75A on onconase structure: Studies at atomic resolution

Katarzyna Kurpiewska1, Gerard Torrent, Marc Ribó

  • 1Faculty of Chemistry, Department of Crystal Physics and Crystal Chemistry, Protein Crystallography Group, Jagiellonian University, Ingardena 3, Kraków, 30060, Poland.

Biopolymers
|September 3, 2013
PubMed

Insights

The double mutant onconase C30A/C75A shows minor structural changes with altered Lys31 conformation, leading to reduced catalytic efficiency and thermal stability.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Enzymology

Background:

  • Onconase is a ribonuclease with therapeutic potential.
  • Understanding enzyme structure-function relationships is crucial for protein engineering.

Purpose of the Study:

  • To determine the high-resolution crystal structure of the onconase C30A/C75A double mutant.
  • To investigate the structural basis for changes in catalytic efficiency and thermal stability.

Main Methods:

  • X-ray crystallography at 1.12Å resolution.
  • Structural comparison with wild-type and other onconase variants.
  • Analysis of molecular packing and solvent accessibility.

Main Results:

  • The C30A/C75A double mutant structure is highly homologous to other onconase structures.
  • Mutations induced small, asymmetric structural changes extending throughout the molecule.
  • Altered Lys31 side chain conformation impacts the catalytic triad's hydrogen bonding network.
  • The double mutant exhibits decreased catalytic efficiency and thermal stability.
  • Reduced thermal stability correlates with less dense molecular packing, increased molecular volume, and larger solvent accessible surface area.

Conclusions:

  • The Lys31 side chain conformation is critical for onconase catalytic activity.
  • Structural alterations associated with mutations affect enzyme stability.
  • High-resolution structural data provides insights into onconase protein engineering for improved therapeutic properties.
Keywords:
atomic resolutiondouble mutant onconaseprotein engineeringranpirnase

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