| Vibrio parahaemolyticus is a Gram-negative halophilic bacterium,that inhabits estuarine and coastal waters and can be isolated from seafoodwith warm climate conditions.humans after the consumption of raw or undercooked seafoodinfected with the bacteria,can make acute gastroenteritis and wound infection,and in severe cases can lead to sepsis.Dsb A protein(disulfide bond formation protein A)is contained in the periplasm between the outer and inner membranes of V.parahaemolyticus.This protein belongs to the disulfide bond oxidoredutase A(Dsb)family.This type of protein can catalyze the formation of disulfide bonds in the periplasmic space of substrate proteins with cysteine residues.Able to fold to form the correct spatial conformation and obtain function.V.parahaemolyticus has two dsb A genes,which are located on chromosomes I and II,and are named dsb A1(VP3054)and dsb A2(VPA1271).Many studies have found that the Dsb family is closely related to the pathogenicity of bacteria,but in V.parahaemolyticus,what molecular mechanism does Vp Dsb A affect the expression of its virulence genes?In order to test whether Vp Dsb A of V.parahaemolyticus has an effect on the pathogenicity of bacteria? this study used three animal models including zebrafish,mouse and drosophila melanogaster to compare the mutants of the dsb A gene deletion mutant of V.parahaemolyticus with wild type strains.survival rate among these three animals.The results showed that compared with wild-type strains,the lethality of dsb Asdeficient mutants of V.parahaemolyticus in these three animal models was significantly reduced,indicating that the pathogenicity of V.parahaemolyticus Dsb A protein has an important role on pathogenicity.So,how does Dsb A affect the pathogenicity of V.parahaemolyticus? To answer this question,we will further explore the effect of Dsb A protein on the function of pathogenic factors of V.parahaemolyticus.Type Ⅲ secretion system(T3SS)is an important virulence factor of V.parahaemolyticus.It was found through infection of Hela cells that Dsb As can affect its cytotoxicity through T3SS1.Transcription and protein level analysis of T3SS1 effector,using RT-PCR and Western blot analysis,found that Vp Dsb A has no significant effect on T3SS1 effector and regulatory factors at the transcription level,but Vp Dsb A can enhance T3SS1 effector protein VPA0450,but another The protein level of effector protein VP1683 has a negative regulatory effect.Therefore,Vp Dsb A may affect the cytotoxicity of V.parahaemolyticus by affecting the protein levels of T3SS1 effector proteins VPA0450 and VP1683.This study also found that Vp Dsb A can affect its hemolytic activity by affecting the expression of hemolysin TDH protein.In addition,the adhesion of V.parahaemolyticus to host cells is also closely related to its pathogenicity.V.parahaemolyticusdsb A deletion mutant infect intestinal epithelial cells(Caco-2 cells)found that the adhesion rate of Vpdsb A mutants stains was significantly lower than that of wild-type strains,and that the adhesion ratewas restored after dsb A supplementation.This shows that Vp Dsb A can affect its pathogenicity by affecting the adhesion of V.parahaemolyticus to host cells.Through analysis of gene transcription and translation levels of various adhesion factors of V.parahaemolyticus such as Vpad F,MAM7,Pil A,Msh A,it was found that the expression of Vpad F protein in dsb As deletion mutant strain(ΔVpdsb A1/2)was significantly reduced.This shows that Vp Dsb A affects the adhesion ability of V.parahaemolyticus by affecting the expression of the adhesion factor Vpad F protein.In a word,Vp Dsb A regulates the pathogenic effects of V.parahaemolyticus from all sides by affecting the physiological functions such as bacterial swarming,cytotoxicity,hemolysis,and adhesion.This paper clarifies the molecular mechanism in which the Dsb A protein of V.parahaemolyticus affects the pathogenicity,and provides an important theoretical basis for further understanding the pathogenic mechanism of V.parahaemolyticus. |
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