Proteomics Profile of Cronobacter sakazakii and fliF Mutant: Adherence and Invasion to Mouse Neuroblastoma Cells

Abstract

Background: Cronobacter sakazakii is an opportunistic foodborne pathogen associated with necrotizing enterocolitis, bacteraemia, and meningitis in infants. A comparative proteomic study of C . sakazakii ATCC BAA-894 (CS WT) and isogenic mutant of flagella were performed; including the ability of both strains to adhere and invade to N1E-115 cells. Results: To achieve this goal, a non-motile C. sakazakii ATCC BAA-894 fliF ::Tn5 (CS fliF ::Tn5) strain was generated using an EZ-Tn5Tnp Transposome kit. Analysis of differential protein expression showed that 81.49% (361/443) of the proteins were identified in both strains, 8.35% (37/443) were exclusively expressed in the CS WT strain and 10.16% (45/443) in the CS fliF ::Tn5 strain. The main exclusive proteins from the CS WT strain were classified into the following subcategories: “cell motility” and “signal transduction mechanisms”. In contrast, the exclusive proteins from the CS fliF ::Tn5 strain were classified into the following subcategories: “intracellular trafficking, secretion, and vesicular transport”, “replication, recombination, and repair”, “nucleotide transport and metabolism”, “carbohydrate transport and metabolism”, “coenzyme transport and metabolism”, and “lipid transport and metabolism”. Expression of the Cpa protein was shared by both strains but was more abundant in the CS WT strain than in the CS fliF ::Tn5 strain. Significant increases (p=0.0001) in adherence to N1E-115 cells were observed for the non-motile CS fliF ::Tn5 strain, with 31.3×10 6 CFU/mL, relative to the CS WT strain, with 14.5×10 6 CFU/mL. Additionally, for infection of N1E-115 cells, the CS WT strain showed a 0.17% invasion frequency, which was significantly increased (p=0.01) compared to that of the non-motile CS fliF ::Tn5 strain. Conclusion : The proteins involved in motility were mainly identified by proteomic analysis in CS WT strain when compare to CS fliF ::Tn5 strain. Our data showed that flagella are required to promote invasion to N1E-115 cells and absence of flagella significantly increases the adherence to N1E-115 cells when compare to CS WT strain.

Characterization of Cronobacter sakazakii and Cronobacter malonaticus Strains Isolated from Powdered Dairy Products Intended for Consumption by Adults and Older Adults

“…Flagellum synthesis is crucial for motility, adhesion, and invasion in bacteria, and the detection of flagellar proteins such as FlgE, FlgL, and FliC in the studied strains of C. sakazakii and C. malonaticus plays a crucial role in their pathogenesis [22,76], as well as the presence of outer membrane proteins like OmpA and OmpX [77,78]. Additionally, we identified the presence of the fic gene, which encodes a toxin, and the relB gene, responsible for the production of the antitoxin relE, both forming part of a bicistronic toxin-antitoxin (TA) operon.…”