Crystal structure of human PLD1 provides insight into activation by PI(4,5)P₂ and RhoA.

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Phospholipase D1 (PLD1) is a signal transduction enzyme.
• PLD1 hydrolyzes phosphatidylcholine to generate phosphatidic acid, a lipid second messenger implicated in thrombosis and cancer.
• PLD1 activity is regulated by protein kinase C, Arf and Rho GTPases, and phosphatidylinositol-4,5-bisphosphate (PIP2).

Purpose of the Study:

• To elucidate the structural basis of human PLD1 regulation by its effectors.
• To provide insights for the rational design of PLD1 inhibitors.

Main Methods:

• X-ray crystallography of the human PLD1 catalytic domain at 1.8 Å resolution.
• Mapping of PLD1 mutations affecting RhoA activation.

Main Results:

• The crystal structure reveals a globular fold with a funnel-shaped hydrophobic cavity leading to the active site.
• A PIP2-binding polybasic pocket at the membrane interface is crucial for PLD1 activity.
• The C terminus contributes to the catalytic pocket, containing a phosphohistidine intermediate.
• The RhoA-PLD1 binding interface was identified through mutation analysis.

Conclusions:

• The structure provides a detailed understanding of PLD1's interaction with lipid and protein regulators.
• This structural information can guide the development of targeted inhibitors for PLD1-related diseases.