Background
Streptococcus agalactiae (GBS) are the major cause of serious diseases of newborns and adults. Genes of toxin-antitoxin system Epsilon/Zeta localized on GBS pathogenicity island PAI-A. The Zeta toxin phosphorylates uridine diphosphate-N-acetylglucosamine (peptidoglycan precursor) that lead to miss assembly of the cell wall. The aim of this investigation was to determine the influence of Zeta toxin gene overexpression on different E.coli strains.
Methods
pQE32 vector contained the insert of zeta (pQE32zeta) was transformed to E. coli strains: BL21, JM109 and DH5α. 20 µl of 10-fold serial dilutions of overnight E. coli cultures were dropped on LB plates with 100 µg/ml ampicillin, 0.1M IPTG and only with 100 µg/ml ampicillin (as control). Next day CFUs were counted.
Results
Strains BL21, JM109, and DH5α contained pQE-32zeta were obtained. Toxic properties of Zeta toxin were evaluated by using induction of Zeta toxin gene expression in different E. coli strains. zeta overexpression led to: 1 – bacterial growth only on first or second dilutions in all E. coli strains under investigation; 2 – complete absence of DH5α bacterial growth on LB plates with 100 µg/ml ampicillin. After induction cells stopped to grow on LB plates with 100 µg/ml ampicillin. Bacterial growth were observed only on LB plates without ampicillin.
Conclusions
Influence of Zeta toxin gene overexpression in E. coli strains led to inhibition of bacterial growth. Bactericidal properties of streptococcal Zeta toxin was determined in E. coli, but the effect was strain dependent.