Subunit interface mutation disrupting an aromatic cluster in Plasmodium falciparum triosephosphate isomerase: effect...

Area of Science:

• Biochemistry
• Structural Biology
• Parasitology

Background:

• Plasmodium falciparum triosephosphate isomerase (PfTIM) is crucial for parasite survival.
• The dimer interface plays a key role in PfTIM stability and function.
• Understanding protein-protein interactions is vital for drug development.

Purpose of the Study:

• To investigate the role of tyrosine 74 at the PfTIM dimer interface.
• To characterize the stability and enzymatic activity of a Y74G PfTIM mutant.
• To elucidate the structural consequences of disrupting subunit interactions.

Main Methods:

• Site-directed mutagenesis to create the Y74G mutant.
• Protein stability assays using denaturing agents (urea, guanidinium chloride).
• Spectroscopic techniques (fluorescence, circular dichroism) to assess protein structure.
• Enzymatic activity assays and analytical gel filtration to study protein behavior.

Main Results:

• The Y74G mutant exhibited significantly reduced stability compared to wild-type PfTIM (TIMWT).
• Spectroscopic studies indicated similar folded structures for both mutant and wild-type proteins.
• The Y74G mutant showed concentration-dependent loss of enzymatic activity, forming predominantly structured monomers at low concentrations.
• Increased exposure of Trp11 was observed in the Y74G mutant, suggesting altered interface dynamics.

Conclusions:

• Mutation of Tyr74 at the PfTIM dimer interface weakens subunit-subunit interactions.
• The Y74G mutation leads to the formation of structured, enzymatically inactive monomers.
• These findings highlight the importance of the dimer interface for PfTIM's stability and catalytic activity.