Identification and verification of novel Type 6 secretion system effectors using a new bioinformatics approach

Bacterial communities are home to very complex microbial interactions. The competition between different bacterial species in a given microbiome over the limited resources of the specific environment leads to an everlasting arms race in which bacterial species are competing with other bacterial or eukaryotic species in order to survive.

Different bacteria evolved various mechanisms that are aimed to destroy competing species. One mechanism is the use of phage tail-like structures that inject toxins into the other species cell, and cause damage.

The type 6 secretion system (T6SS) is one example of these mechanisms. Some of the effectors of this secretion system are already known but it is very likely that throughout evolution many more effectors have evolved and are undiscovered. Moreover, most of the bacteria encoding T6SS operons lack any known effector.

Using a novel bioinformatic tool that scans sequenced microbiomes of various environments, our lab has identified candidate genes that are predicted to be toxins secreted by these phage like structures.

We are using multiple biological techniques in order to verify the toxicity of these predicted genes against bacteria and yeast, and study their mechanism of action and the function of various secretion systems.

We also perform biochemical assays to identify new adaptor proteins that match between effectors and the T6SS apparatus.

Finding more effectors that are aimed towards fighting microbes on the plant will eventually lead to a better understanding of these specialized mechanisms, and an important insight into inter-bacterial warfare.