Sperm chromatin-condensing protamine enhances SMYD5 thermal stability

Area of Science:

• Biochemistry and Structural Biology
• Molecular Biology
• Computational Biology

Background:

• Protein thermal stability studies offer insights into protein structure and interactions.
• Identifying molecules that enhance protein stability can reveal novel interaction partners.
• Histone lysine methyltransferases, like SMYD5, play crucial roles in regulating chromosome integrity.

Purpose of the Study:

• To develop and apply a machine learning strategy to identify molecules that enhance protein stability.
• To investigate the structural stability of SMYD5, a histone lysine methyltransferase.
• To explore the potential functional link between SMYD5 and spermatogenesis.

Main Methods:

• Combined orthogonal partial least squares regression with stability screening of the Silver Bullets Bio library.
• Utilized a machine learning strategy to identify stability-enhancing molecules.
• Investigated the role of specific SMYD5 structural features (poly-E tract and M-insertion) and protamine interaction on thermal stability.

Main Results:

• Identified protamine as the most influential molecule enhancing SMYD5 thermal stability.
• Discovered that unique SMYD5 features (poly-E tract and M-insertion) regulate stability, but protamine's effect is dominant.
• Demonstrated that protamine's stabilizing effect is specific to SMYD5, with opposite effects on the related SMYD2 homolog.

Conclusions:

• Protamine significantly enhances SMYD5 thermal stability, providing insights into its structure-stability relationships.
• SMYD5 interaction with protamine is independent of its unique structural elements.
• The findings suggest a potential functional link between SMYD5 and spermatogenesis, given its high expression in testis.