Identification of Vibrio cholerae type III secretion system effector proteins

Area of Science:

• Microbiology
• Molecular Biology
• Pathogenesis

Background:

• Vibrio cholerae strain AM-19226 lacks typical virulence factors but possesses a type III secretion system (T3SS).
• The pathogenesis mechanism and effector proteins of this strain are largely unknown.

Purpose of the Study:

• To identify potential effector proteins encoded by the T3SS genomic island in V. cholerae AM-19226.
• To characterize the function and regulation of these identified effectors.

Main Methods:

• Screening of open reading frames (ORFs) for growth inhibition in yeast.
• Utilizing a TEM1 fusion reporter system to confirm T3SS-dependent translocation of effectors into HeLa cells.
• Investigating the in vivo colonization role and in vitro expression regulation of the VopX effector.

Main Results:

• Fifteen ORFs were identified for growth inhibition, and 11 were confirmed as T3SS-dependent effectors.
• VopX (A33_1663) was identified as a novel, conserved effector.
• VopX deletion reduced in vivo colonization, and its expression is bile-induced and T3SS-regulated.
• VopX likely interacts with the cell wall integrity MAPK pathway.

Conclusions:

• The V. cholerae T3SS encodes multiple effector proteins that contribute to pathogenesis.
• VopX is a novel effector that interferes with eukaryotic signaling pathways, impacting V. cholerae virulence.