Journal Article

Vibrio effector protein VopQ inhibits fusion of V-ATPase–containing membranes

Carpinone, Emily M., Starai, Vincent J., O’Brien, Kevin M., Bennett, Terry L., Sreelatha, Anju, Jordan, Kamyron D., Orth, Kim, Burdette, Dara L.

2015

Overview

Vesicle fusion governs many important biological processes, and imbalances in the regulation of membrane fusion can lead to a variety of diseases such as diabetes and neurological disorders. Here we show that the Vibrio parahaemolyticus effector protein VopQ is a potent inhibitor of membrane fusion based on an in vitro yeast vacuole fusion model. Previously, we demonstrated that VopQ binds to the V ₒ domain of the conserved V-type H ⁺-ATPase (V-ATPase) found on acidic compartments such as the yeast vacuole. VopQ forms a nonspecific, voltage-gated membrane channel of 18 Å resulting in neutralization of these compartments. We now present data showing that VopQ inhibits yeast vacuole fusion. Furthermore, we identified a unique mutation in VopQ that delineates its two functions, deacidification and inhibition of membrane fusion. The use of VopQ as a membrane fusion inhibitor in this manner now provides convincing evidence that vacuole fusion occurs independently of luminal acidification in vitro. Significance Fusion of intracellular membranes is involved in many critical cellular processes, such as neurotransmission, protein trafficking, and in the lysosomal degradation of invading bacterial pathogens. Accordingly, some intracellular bacterial pathogens use protein effectors to alter host membrane fusion directly as a survival mechanism. In this study, we show that the Vibrio secreted effector, VopQ, is a potent inhibitor of yeast homotypic vacuole fusion in vitro. Although VopQ was shown to deacidify yeast vacuoles via its known V-type H ⁺-ATPase (V-ATPase)-binding and channel-forming activities, its ability to inhibit vacuole fusion does not depend on channel-forming activity. Our studies suggest that yeast vacuole fusion is not regulated by lumenal acidification and identify a reagent to study the V-ATPase role in some membrane fusion events.

• Publisher: National Academy of Sciences
• Subject: Acidification / Acids - metabolism / Adenosine triphosphatase / Bacterial proteins / Bacterial Proteins - metabolism / Biochemistry / Biological Sciences / Electrochemistry / Gram-negative bacteria / H-transporting ATP synthase / Hydrogen-Ion Concentration / Ion Channels - metabolism / Lipids - chemistry / Membrane Fusion / Membranes / Mutant Proteins - metabolism / Mutation / Neutralization / pathogens / protein transport / Saccharomyces cerevisiae - metabolism / SNARE Proteins - metabolism / Vacuolar Proton-Translocating ATPases - metabolism / vacuoles / Vacuoles - metabolism / Vibrio / Vibrio parahaemolyticus / Vibrio parahaemolyticus - metabolism / Yeast / Yeasts