It turns out that microbes account for about half of life on our planet. We are only appreciating recently how much these unseen (and unsung) heroes shape our environment and ourselves. In particular, bacteria are now understood to affect our diet and possibly our brain development. 

In order to be able to interact with their environment, bacteria rely greatly on a set of different external appendages. Of all of these appendages, one of them is ubiquitous, being found in every single known phyla. This is the Type Four Pilus (TFP).

TFP are extremely versatile nanomachines enabling the extrusion of a polymer of the major pilin with diameters of 4 to 10 nm but length reaching 100 μm.

Besides, the functions associated with these polymers are staggering, from mere adhesion to motility to DNA uptake and electron conduction. One of the reasons for this incredible multifunctionality is the dynamical nature of these polymers.

TFP undergoes cycles of elongations and retractions. The forces they can exert span 3 orders of magnitudes from a few pN to nanoNewtons, making them the strongest molecular machine measure to date. They can undergo dramatic structural changes when sustaining physical forces. And they have recently emerged as bacterial mechanosensors conferring a sense of touch to bacteria.

The goal of this project is to use fluorescent microscopy and microfabricated devices to unravel the mechanisms at play in the functions of this ubiquitous and omnipresent bacterial appendage. The candidate will learn to measure the forces exerted by TFP and follow by fluorescence their structural changes. If you are interested and want to know more do not hesitate to  contact me:

Nicolas Biais, Professor of Cellular Biomechanics, Laboratoire Jean Perrin,

Nicolas@mechano-micro-biology.org or Nicolas.Biais@sorbonne-universite.fr