Characterization of a novel zinc transporter ZnuA acquired by Vibrio parahaemolyticus through horizontal gene transfer

Ming Liu,Meiying Yan,Sheng Chen,Lizhang Liu

doi:10.3389/fcimb.2013.00061

Abstract

Vibrio parahaemolyticus is a clinically important foodborne pathogen that causes acute gastroenteritis worldwide. It has been shown that horizontal gene transfer (HGT) contributes significantly to virulence development of V. parahaemolyticus. In this study, we identified a novel znuA homolog (vpa1307) that belongs to a novel subfamily of ZnuA, a bacterial zinc transporter. The vpa1307 gene is located upstream of the V. parahaemolyticus pathogenicity island (Vp-PAIs) in both tdh-positive and trh-positive V. parahaemolyticus strains. Phylogenetic analysis revealed the exogenous origin of vpa1307 with 40% of V. parahaemolyticus clinical isolates possessing this gene. The expression of vpa1307 gene in V. parahaemolyticus clinical strain VP3218 is induced under zinc limitation condition. Gene deletion and complementation assays confirmed that vpa1307 contributes to the growth of VP3218 under zinc depletion condition and that conserved histidine residues of Vpa1307 contribute to its activity. Importantly, vpa1307 contributes to the cytotoxicity of VP3218 in HeLa cells and a certain degree of virulence in murine model. These results suggest that the horizontally acquired znuA subfamily gene, vpa1307, contributes to the fitness and virulence of Vibrio species.

Highlights

Vibrio parahaemolyticus is a motile and facultative anaerobe that frequently inhabits in estuarine and marine environments
Comparative genomic analysis of pre-pandemic and pandemic V. parahaemolyticus strains, as well as molecular profiling studies, revealed that the organization of mobile gene cassettes and pathogenicity islands were divergent in these V. parahaemolyticus strains and that the emergence of pandemic strain could be associated with the recombination events and novel gene acquisition (Hurley et al, 2006; Gonzalez-Escalona et al, 2008; Han et al, 2008; Caburlotto et al, 2011; Chen et al, 2011; Yan et al, 2011; Garcia et al, 2012; Gennari et al, 2012; Gavilan et al, 2013; Ottaviani et al, 2013; Theethakaew et al, 2013; Turner et al, 2013)
BIOINFORMATICS ANALYSIS OF THE vpa1307 GENE AND ITS DISTRIBUTION IN V. parahaemolyticus Since PAI is important for the virulence, we focused on genes related to V. parahaemolyticus pathogenicity island (Vp-PAIs) (Dobrindt et al, 2004)

Summary

Introduction

Vibrio parahaemolyticus is a motile and facultative anaerobe that frequently inhabits in estuarine and marine environments. It is a well-known pathogen that leads to acute gastroenteritis worldwide, especially in areas with high level consumption of seafood such as raw oysters and shrimps (Blake et al, 1980). The pathogenicity of this pathogen is highly associated with the thermostable direct hemolysin (TDH), TDH-related hemolysin (TRH), and two type III secretion systems (T3SSs), T3SS1 and T3SS2 (Shirai et al, 1990; Hiyoshi et al, 2010). The genetic divergence of V. parahaemolyticus strongly correlates with their diverse virulence potentials (Vongxay et al, 2008; Caburlotto et al, 2010)

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Conclusion