Prophage-Related Gene VpaChn25_0724 Contributes to Cell Membrane Integrity and Growth of Vibrio parahaemolyticus CHN25

Abstract

Vibrio parahaemolyticus is a leading seafood-borne pathogen that can cause acute gastroenteritis and even death in humans. In aquatic ecosystems, phages constantly transform bacterial communities by horizontal gene transfer. Nevertheless, biological functions of prophage-related genes in V. parahaemolyticus remain to be fully unveiled. Herein, for the first time, we studied one such gene VpaChn25_0724 encoding an unknown hypothetical protein in V. parahaemolyticus CHN25. This gene deletion mutant ΔVpaChn25_0724 was constructed by homologous recombination, and its complementary mutant ΔVpaChn25_0724-com was also obtained. The ΔVpaChn25_0724 mutant exhibited a sever defect in growth and swimming motility particularly at lower temperatures. Biofilm formation and cytotoxicity capacity of V. parahaemolyticus CHN25 was significantly lowered in the absence of VpaChn25_0724. Comparative secretomic analysis revealed an increase in extracellular proteins of ΔVpaChn25_0724, which likely resulted from its damaged cell membrane. Comparison of transcriptome data showed twelve significantly altered metabolic pathways in ΔVpaChn25_0724, suggesting inactive transport and utilization of carbon sources, repressed energy production and membrane biogenesis in ΔVpaChn25_0724. Comparative transcriptomic analysis also revealed several remarkably down-regulated key regulators in bacterial gene regulatory networks linked to the observed phenotypic variations. Overall, the results here facilitate better understanding of biological significance of prophage-related genes remaining in V. parahaemolyticus.

Prophage-encoded gene VpaChn25_0734 amplifies ecological persistence of Vibrio parahaemolyticus CHN25

“…Vibrio parahaemolyticus CHN25 (Song et al 2013 ; Sun et al 2014 ; He et al 2015 ; Zhu et al 2017 , 2020 ; Yang et al 2020 ) was stored at − 80 °C freezer in our research group. Escherichia coli DH5α λpir (BEINUO Biotech (Shanghai) Co. Ltd., China), E. coli β2155 λpir (kindly provided by Professor Weicheng Bei) and plasmid pDS132 (kindly provided by Professor Dominique Schneider) were used as a host strain for gene cloning, and a donor strain and a suicide vector for conjugation and gene knockout experiments, respectively (Zhu et al 2017 ; Yang et al 2020 ). Plasmid pMMB207 (Biovector Science Lab, Inc., China) was used as a gene expression vector (Zhu et al 2017 ; Yang et al 2020 ).…”

“…In our previous research, V. parahaemolyticus CHN25 (serotype: O5: KUT) of aquatic animal origin was identified and characterized (Song et al 2013 ; Sun et al 2014 ; He et al 2015 ; Zhu et al 2017 , 2020 ; Yang et al 2020 ). The bacterial genome (5,443,401 bp, 45.2% G+C) contains five prophage gene clusters (6.5–36.6 kb) (Zhu et al 2017 ), the largest of which showed sequence similarity to a Vibrio phage Martha 12B12 (Zhu et al 2017 ).…”

“…The bacterial genome (5,443,401 bp, 45.2% G+C) contains five prophage gene clusters (6.5–36.6 kb) (Zhu et al 2017 ), the largest of which showed sequence similarity to a Vibrio phage Martha 12B12 (Zhu et al 2017 ). Within the cluster, a gene VpaChn25_0724 (294-bp) encoding a hypothetical protein has been identified recently (Yang et al 2020 ). In the present study, biological function of another prophage-encoded gene VpaChn25_0734 (543-bp) within the same gene cluster was characterized.…”

Adaptations of Vibrio parahaemolyticus to Stress During Environmental Survival, Host Colonization, and Infection

“…The prophages such as Vp58.5, Vp882, and VP06 in Vp enhance the function of ultraviolet sensitivity, DNA methylase, and quorum sense and resist environmental stress, respectively (Lan et al, 2009;Zabala et al, 2009;Wong et al, 2019). Strainspecific Martha12B12 phage that encode a hypothetical proteinencoding gene VpaChn25_0724 was found to not only influence bacterial growth, motility, biofilm formation, production of secretomes, and also protects bacteria against host phagocytosis (Yang et al, 2020).…”

“…Conversion of viable but nonculturable (VBNC) from biofilm formation, quorum sensing regulators, and toxin-antitoxin systems are activated in response to various environmental conditions (Letchumanan et al, 2017;Banerjee et al, 2018). In addition, the intake of prophages and horizontal gene transfer into bacterial chromosomes enhance fitness of the pathogen to encounter several adverse changes in the host (Yang et al, 2020). This review highlights the gaps in our knowledge on how the inherent and acquired factors enhance adaptive mechanisms in Vp that mark the pathogen to survive and enhance the pathogenesis under several stressful conditions.…”