Biomod/2015/UNSW:Our Project

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Ever wondered how Nature can spontaneously build a complex, functional, biological machine on a tiny scale?

Self-assembly is one of Nature’s greatest achievements – and also one of its greatest mysteries! The process behind it remains largely uncharacterised for a whole host or reasons, one of which is the inability to control and visualise self-assembly in action for analysis.

We’re pioneering a novel approach to induce artificial synthesis of a complex in a controlled environment that allows us to test the bounds of assembly. The bacterial type 3 secretion system (T3SS), also known as the Injectisome, is an ideal model for spontaneous self-assembly of a functional, multimeric protein machine. Though tiny in size, it is a mega-Dalton complex that mediates bacteria-host relationships in many human pathogens.

When the bacterial cell comes into contact with a host cell, a signal fires that triggers the construction of the needle, capped by a pentamer structure that folds right there on the tip.

But how?

Our theory is that this tip complex forms because it uses the needle as a scaffold for assembly.



We want to artificially assembly the tip of this bacterial Injectisome, using a DNA template as a scaffold.

With the use of protein engineering and production, DNA design, and protein conjugation, we hope to attach the tip proteins to the scaffold, and induce interactions between the proteins to form the pentamer.

To test for our final product, we’re using single molecule fluorescence, electron microscopy, AFM and SAX to visualise our complex. We’re also characterising the interactions with the use of biolayer interferometry, to churn out the kinetic and thermodynamic models of the assembly.

Wanna know exactly how we’re doing this? Check out our lab book here!



This synthetic approach to construction gives an experimental platform for further studies in assembly of complex nanomachines in a controlled, but “natural” environment. Parts of a system can be studied in detail, without losing the context of structure as a whole.

It also opens the door to development of new technologies. We’re able to build complex antigens, which have the potential to become the basis of new, more effective vaccines against prevalent diseases in the world today.

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