Ankyrin repeats as a dimerization module

Area of Science:

• Microbiology
• Structural Biology
• Protein Science

Background:

• Legionella pneumophila causes Legionnaires' disease, a severe pneumonia.
• AnkC (LegA12) is a conserved, yet poorly understood, effector protein from Legionella species.

Purpose of the Study:

• To determine the crystal structure of a truncated AnkC protein.
• To elucidate the structural basis of AnkC's function and dimerization.

Main Methods:

• X-ray crystallography to obtain the AnkC (2-384) structure at 3.2 Å resolution.
• Analytical ultracentrifugation to confirm dimerization in solution.

Main Results:

• The structure revealed seven ankyrin repeats (ARs) with unique features.
• AnkC forms a dimer via its ARs, a novel dimerization mechanism.
• A unique α-helix insert was identified between AR3-AR4.
• The ankyrin groove is conserved, suggesting it's a functional interaction site.

Conclusions:

• This study presents the first structural insights into AnkC, a key Legionella effector.
• The ankyrin repeats of AnkC function as a dimerization module.
• The structure provides a foundation for future functional studies of AnkC.