The development of antibiotics has revolutionized medicine, however the rise in antibiotic-resistant
bacteria has pushed scientists to explore alternative strategies such as bacterial secretion systems as
an alternative tool against bacterial infections. This research explores the dynamics of the Type VI
secretion system (T6SS) effectors, specifically studying the effector's toxic activity and immunity
to its own toxin. We aimed to investigate a novel putative periplasmic effector discovered in
pathogenic Vibrio species, Tme1 (Type VI membrane-disrupting effector), and its impact on
bacterial cell survival. Working with pathogenic Vibrio is dangerous, thus we examined its activity
by ectopically expressing it in a safe, model organism Escherichia coli (E. coli). By expressing the
effector inside the prey cells, we bypassed the need for delivery mechanisms in order to assess the
toxic potential of the effector without the requirement of secretion by the T6SS. We hypothesized
that the effector Tme1, expressed ectopically in E. coli , will exert toxic activity. In the study we
conducted various research methods such as transformation by electroporation, polymerase chain
reaction (PCR) experiment, toxicity assays in both liquid and solid media, and protein expression
assays.
Our findings partially aligned with our hypothesis, the periplasmic toxic effector Tme1 exhibited
anticipated toxicity in solid media. Although surprisingly in liquid media the only effectors which
revealed toxicity in both the periplasm and the cytoplasm were the immunity proteins. This resulted
in statistical analysis showing no significant difference in toxicity between periplasmic and
cytoplasmic effectors. These interesting and intriguing results not only show the potential for
developing tools against bacterial infections using toxic effector Tme1 but prompt further
investigation into underlying mechanisms of the immunity effector. Overall, the study contributed
to the understanding of bacterial warfare mechanisms and opens new avenues for exploration and
contributing to the ongoing efforts in addressing antibiotic resistance.