Polymorphism of the glycerol-3-phosphate oxidase gene as one of the Mycoplasma Pneumoniae genetic features influencing the formation of pathogenicity factors

Abstract

Objective: to identify possible genetic variants of Mycoplasma pneumoniae in a glycerol-3-phosphate oxidase gene fragment corresponding to the FAD binding domain of the enzyme, and to study their pathogenic properties.Material and methods: The material for the obtainment of Mycoplasma pneumoniae isolates was sputum, epithelial cell scrapings from the nasopharynx, tracheobronchial secretion from 85 children and adolescents diagnosed with bronchitis and pneumonia and detecting Mycoplasma pneumoniae DNA. The isolation of Mycoplasma pneumoniae from the clinical material was proceeded in a mycoplasma medium without an energy source. The DNA isolation from the biological material and from the culture fluid was performed by the method of sorption extraction. The sediment of the cellular elements of the sputum was used for the DNA extraction with the use of the CTAB reagent.Results. Synonymous and non-synonymous nucleotide substitutions have been identified in 54 clinical isolates of Mycoplasma pneumoniae . It has been found that the amino acid substitutions His51Leu and Asp55His are essential for the realization of the pathogenic potential of the Mycoplasma pneumoniae isolates associated with the production of hydrogen peroxide. Conclusion. The A152T (His51Leu) and G163C (Asp55His) substitutions were identified in the G3P oxidase gene of the Mycoplasma pneumonia clinical isolates, and their presence was associated with the variability in the activity of the enzyme. The Mycoplasma pneumoniae isolates carrying the A152T substitution (His51Leu) produced hydrogen peroxide in significantly lower amounts (5 mg/l) in comparison with the reference strain (10 mg/l) and had reduced cytotoxicity in relation to respiratory epithelial cells. The Mycoplasma pneumoniae isolates carrying the substitution G163C (Asp55His) were characterized by enhanced pathogenic properties, such as increased production of hydrogen peroxide (25 mg/l) and more pronounced cytotoxicity towards respiratory epithelial cells.