Role of Maturation of Lipoproteins in the Pathogenesis of the Infection Caused by Streptococcus suis Serotype 2

Abstract

Streptococcus suis serotype 2 is an important porcine bacterial pathogen associated with multiple pathologies in piglets. Bacterial lipoproteins (LPPs) have been described as playing important roles in the pathogenesis of the infection of other Gram-positive bacteria as adhesins, pro-inflammatory cell activators and/or virulence factors. In the current study, we aimed to evaluate the role of the prolipoprotein diacylglyceryl transferase (Lgt) and lipoprotein signal peptidase (Lsp) enzymes, which are responsible for LPP maturation, on the pathogenesis of the infection caused by two different sequence types (STs) of S. suis serotype 2 strains (virulent ST1 and highly virulent ST7). Through the use of isogenic Δlgt, Δlsp and double Δlgt/Δlsp mutants, it was shown that lack of these enzymes did not influence S. suis adhesion/invasion to porcine respiratory epithelial cells. However, in the absence of the Lsp and/or Lgt, a significant reduction in the capacity of S. suis to activate phagocytic cells and induce pro-inflammatory mediators (in vitro and in vivo) was observed. In general, results obtained with the double mutant did not differ in comparison to single mutants, indicating lack of an additive effect. Finally, our data suggest that these enzymes play a differential role in virulence, depending on the genetic background of the strain and being more important for the highly virulent ST7 strain.

Bacterial outer membrane vesicles and their functionalization as vehicles for bioimaging, diagnosis and therapy

“…Meanwhile, lipoprotein diacylglyceryl transferase (Lgt) is required for lipidation and maturation of Lpp by catalyzing the acylation of Lpp. 17 The mutation of Lgt leads to lack of Lpp, which increases the cytoplasmic membrane fluidity and vesicle formation of E . coli .…”

“…Meanwhile, lipoprotein diacylglyceryl transferase (Lgt) is required for lipidation and maturation of Lpp by catalyzing the acylation of Lpp. 17 The mutation of Lgt leads to lack of Lpp, which increases the cytoplasmic membrane fluidity and vesicle formation of E. coli. 18 Furthermore, the removal of LPS with detergents, such as EDTA, is a traditional method to increase the vesicle release and has been widely used for scale up.…”

Study of the Role of Lipoprotein Maturation Enzymes in the Pathogenesis of the Infection Caused by the Streptococcus suis Serotype 2 Sequence Type 25 North American Prototype Strain

“…The majority of these factors have been described using Eurasian ST1 or ST7 serotype 2 strains. LPPs, a major class of surface proteins of this and other bacterial pathogens [8], are mainly anchored in the outer leaflet of the cytoplasmic membrane. Bacterial LPPs have been shown to perform various roles, such as nutrient uptake, signal transduction as well as a participation in antibiotic resistance and transport systems (such as ABC transporters) [9].…”

“…Bacterial LPPs have been shown to perform various roles, such as nutrient uptake, signal transduction as well as a participation in antibiotic resistance and transport systems (such as ABC transporters) [9]. In addition, they have been shown to play a direct role in virulence-associated functions, such as colonization, adhesion and invasion, evasion of host defense, and immunomodulation [8,[10][11][12][13]. LPPs are first translated as preprolipoproteins, which possess an N-terminal signal peptide with typical characteristic features of the signal peptides of secreted proteins.…”

“…A recent study suggests that LPP maturation in S. suis regulates dendritic cell activation in vitro and host activation after infection. In addition, these enzymes seem to play a differential role in virulence depending on the genetic background of the strain (ST1 vs. ST7) [8]. It has been reported that, as different from Eurasian strains, the CPS of a North American S. suis serotype 2 ST25 representative strain only partially masks sub-capsular domains and bacterial wall components [16][17][18].…”