Structures of the heart specific SERCA2a Ca²⁺-ATPase

Area of Science:

• Biochemistry
• Structural Biology
• Cardiovascular Physiology

Background:

• The sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) is crucial for cardiac muscle contractility.
• SERCA2a dysfunction is linked to heart failure, making it a therapeutic target.
• The structure of SERCA2a has remained undetermined until now.

Purpose of the Study:

• To determine the first crystal structures of SERCA2a.
• To elucidate the structural basis for kinetic differences between SERCA2a and SERCA1a.
• To identify potential sites for post-translational modifications influencing SERCA2a function.

Main Methods:

• Purification of native, active SERCA2a from pig ventricular muscle.
• Determination of crystal structures in CPA-stabilized E2-AlF4- and Ca2+-occluded E1-AMPPCP forms.
• Molecular dynamics simulations to analyze isoform-specific interactions.

Main Results:

• The first crystal structures of SERCA2a were determined at 3.3 Å and 4.0 Å resolution.
• SERCA2a structures show similarity to SERCA1a, suggesting conserved mechanisms.
• Isoform-specific residues were identified as potential post-translational modification sites and support distinct intramolecular interactions.

Conclusions:

• The determined SERCA2a structures provide a foundation for understanding its function in cardiac muscle.
• Isoform-specific residues and their interactions likely explain the kinetic differences between SERCA2a and SERCA1a.
• These findings may guide therapeutic strategies for heart failure by targeting SERCA2a function.