Type IV Pili - multifunctional surface filaments

Many species of bacteria produce long, thin, flexible protein filaments called type IV pili (T4P). These fascinating appendages can be rapidly and repeatedly extended and retracted, allowing the bacteria to use them to capture DNA (like a spear-fishing rod) or to crawl on surfaces (like a grappling hook). They are adhesive, allowing bacteria to stick to all kinds of different surfaces, including the host in the case of pathogens. Bacteria use them to 'feel' surface contact, which then turns on expression of surface-associated genes such as those involved in biofilm formation. They are receptors for bacteriophages (viruses that specifically kill bacteria) and in some species, can even act as wires to conduct electricity!

We study multiple aspects of these amazing filaments. Ongoing projects range from studying the structure and function of the machine that makes the filaments, the motor that extends and retracts them, the diversity of the subunits that make up the filaments and its relationship to phage escape, the regulatory pathways involved in surface sensing, and more!

Biofilms promote antibiotic resistance

Communities of bacteria growing on surfaces are called biofilms. This mode of growth makes the cells more tolerant of disinfectants and antibiotics, making biofilm infections difficult to treat. Pseudomonas aeruginosa, one of our model bacteria, is often used for biofilm studies because it forms biofilms on medical devices such as catheters and contact lenses. It also forms biofilms in the lungs of people with cystic fibrosis, leading to chronic infection and lung damage due to inflammation.


We investigate how biofilms develop in response to chemical cues, particularly antibiotics. Sub-lethal concentrations of antibiotics stimulate biofilm formation – we study how this phenotype is induced, and exploit it to identify new antimicrobials in complex mixtures or compound libraries.

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