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Structural Insights to the Heterotetrameric Interaction between the Vibrio parahaemolyticus PirAvp and PirBvp Toxins and Activation of the Cry-Like Pore-Forming Domain

Authors :
Shin-Jen Lin
Yi-Fan Chen
Kai-Cheng Hsu
Yun-Ling Chen
Tzu-Ping Ko
Chu-Fang Lo
Han-Ching Wang
Hao-Ching Wang
Source :
Toxins, Vol 11, Iss 4, p 233 (2019)
Publication Year :
2019
Publisher :
MDPI AG, 2019.

Abstract

Acute hepatopancreatic necrosis disease (AHPND) is a newly emergent penaeid shrimp disease which can cause 70–100% mortality in Penaeus vannamei and Penaeus monodon, and has resulted in enormous economic losses since its appearance. AHPND is caused by the specific strains of Vibrio parahaemolyticus that harbor the pVA1 plasmid and express PirAvp and PirBvp toxins. These two toxins have been reported to form a binary complex. When both are present, they lead to the death of shrimp epithelial cells in the hepatopancreas and cause the typical histological symptoms of AHPND. However, the binding mode of PirAvp and PirBvp has not yet been determined. Here, we used isothermal titration calorimetry (ITC) to measure the binding affinity of PirAvp and PirBvp. Since the dissociation constant (Kd = 7.33 ± 1.20 μM) was considered too low to form a sufficiently stable complex for X-ray crystallographic analysis, we used alternative methods to investigate PirAvp-PirBvp interaction, first by using gel filtration to evaluate the molecular weight of the PirAvp/PirBvp complex, and then by using cross-linking and hydrogen-deuterium exchange (HDX) mass spectrometry to further understand the interaction interface between PirAvp and PirBvp. Based on these results, we propose a heterotetrameric interaction model of this binary toxin complex. This model provides insight of how conformational changes might activate the PirBvp N-terminal pore-forming domain and should be helpful for devising effective anti-AHPND strategies in the future.

Details

Language :
English
ISSN :
20726651
Volume :
11
Issue :
4
Database :
Directory of Open Access Journals
Journal :
Toxins
Publication Type :
Academic Journal
Accession number :
edsdoj.1b69dec0a684a3187804325b81c0277
Document Type :
article
Full Text :
https://doi.org/10.3390/toxins11040233