Structural effects of substitutions on the p21 proteins

Area of Science:

• Biochemistry
• Molecular Biology
• Oncogenes

Background:

• The p21 protein, encoded by an oncogene, plays a role in cell transformation.
• Mutations substituting glycine at position 12 are linked to malignant cell transformation.
• Understanding the conformational impact of these substitutions is crucial for cancer research.

Purpose of the Study:

• To investigate the conformational effects of various amino acid substitutions at position 12 of the p21 protein.
• To determine if specific substitutions induce a common, malignancy-associated conformation.
• To explore the potential of proline substitution in mitigating the transforming activity of p21.

Main Methods:

• Conformational energy calculations were employed.
• Analysis focused on decapeptides representing the p21-(6-15) region.
• Substitutions included lysine, serine, proline, and D-valine for glycine at position 12.

Main Results:

• Lysine and serine substitutions resulted in more restricted and helical peptide structures compared to glycine.
• Valine, lysine, and serine substitutions favored a common lowest-energy conformation, termed the "malignancy-causing" conformation.
• Proline substitution, unlike valine, lysine, and serine, led to helix termination at positions 11 and 12, similar to glycine.

Conclusions:

• Specific amino acid substitutions at position 12 of p21 can induce a distinct, potentially oncogenic conformation.
• The findings suggest a structural basis for the malignant transformation associated with certain p21 mutations.
• Proline at position 12 may reduce the transforming potential of the p21 protein, aligning with experimental observations.