Structural and Functional Characterization of Legionella pneumophila Effector MavL

Area of Science:

• Microbiology
• Structural Biology
• Molecular Biology

Background:

• Legionella pneumophila causes Legionnaires' disease by injecting effector proteins into host cells.
• The Dot/Icm Type IV Secretion System (T4SS) is crucial for L. pneumophila pathogenesis.
• Understanding effector protein function is key to deciphering bacterial virulence.

Purpose of the Study:

• Determine the crystal structure of the L. pneumophila effector protein MavL.
• Investigate MavL's enzymatic activity and binding properties.
• Identify host factors interacting with MavL.

Main Methods:

• X-ray crystallography to determine MavL structure.
• Biochemical assays to assess ADP-ribose binding and enzymatic activity.
• Yeast two-hybrid and co-immunoprecipitation to identify protein interactions.

Main Results:

• MavL adopts an ADP-ribosyltransferase (ART) fold and binds ADP-ribose (Kd = 13 µM).
• Structural comparisons suggest MavL may function as an ADP-ribose binder rather than a hydrolase.
• MavL interacts with the human ubiquitin-conjugating enzyme UBE2Q1.

Conclusions:

• MavL is a structurally characterized effector of L. pneumophila.
• MavL's binding to ADP-ribose and interaction with UBE2Q1 suggest a role in host manipulation via ADP-ribosylation and ubiquitination.
• This study provides insights into L. pneumophila virulence mechanisms.