Examining protein surface structure in highly conserved sequence variants with mass spectrometry.

Area of Science:

• Biochemistry
• Structural Biology
• Mass Spectrometry

Background:

• Understanding protein structure and the impact of mutations is crucial in biology.
• Existing methods for assessing protein structural changes can be complex or require significant sample amounts.

Purpose of the Study:

• To evaluate the structural consequences of point mutations in naturally occurring protein variants using a novel method.
• To demonstrate the utility of SNAPP for comparing protein surface structures across different species and homologous proteins.

Main Methods:

• Utilized selective noncovalent adduct protein probing (SNAPP), a mass spectrometry-based technique.
• Monitored changes in noncovalent adduct attachment to proteins to assess structural state.
• Applied SNAPP to analyze variants of insulin, cytochrome c, and lysozyme from different species.

Main Results:

• SNAPP successfully detected structural perturbations caused by mutations affecting protein electrostatic surface structure.
• Insulin variants from different species showed similar SNAPP distributions, indicating conserved surface structures.
• Cytochrome c variants displayed varying SNAPP distributions correlating with sequence homology, with yeast cytc showing unique patterns.
• Lysozyme variants with identical tertiary structures but different surface residues exhibited distinct SNAPP distributions.

Conclusions:

• SNAPP is a simple, sensitive method for examining protein structure and the effects of mutations.
• The technique can differentiate subtle and significant changes in protein surface structure.
• SNAPP offers a facile approach for comparing protein structures, even between highly homologous proteins, with minimal sample consumption.