Hydrophobicity-Driven Disruption Mechanism in Kindlin-3 Induced by Leukocyte Adhesion Deficiency Mutation

Area of Science:

• Biochemistry
• Molecular Biology
• Immunology

Background:

• Leukocyte adhesion deficiency type III (LAD-III) is a genetic disorder characterized by impaired integrin activation due to mutations in Kindlin-3.
• The QW motif within Kindlin proteins is crucial for integrin activation, and specific mutations, like Q595P, are linked to LAD-III.
• The precise molecular mechanisms by which Kindlin-3 mutations disrupt integrin function remain incompletely understood.

Purpose of the Study:

• To elucidate the molecular mechanisms by which the pathogenic Q595P mutation in Kindlin-3 affects its interaction with β1-integrin.
• To investigate the impact of the Q595P mutation on binding affinity, specificity, and mechanical stability under physiological conditions.

Main Methods:

• Molecular dynamics (MD) simulations.
• Steered molecular dynamics (sMD) simulations to analyze the Kindlin-3/β1-integrin complex under force.

Main Results:

• The Q595P mutation induces conformational changes in Kindlin-3, reducing binding affinity and mechanical strength with β1-integrin.
• The mutation disrupts the hydrophobic environment at the binding interface, destabilizing crucial hydrogen bonds.
• Enhanced nonspecific hydrophobic interactions were observed, further compromising the stability of the Kindlin-3/β1-integrin complex.

Conclusions:

• Pathogenic mutations in conserved Kindlin-3 regions, such as Q595P, disrupt integrin activation by altering protein dynamics and interactions.
• These molecular alterations provide insights into the pathogenesis of LAD-III.
• The study highlights the critical role of hydrophobic interactions and hydrogen bonding in maintaining Kindlin-3/integrin complex stability.