Microbiology Editor's Choice: type IV warfare in Pseudomonas aeruginosa

Posted on November 1, 2019   by Microbiology Society

Each month, a manuscript published in our flagship journal Microbiology is chosen by a member of the Editorial Board. This month, the paper is titled "PAAR proteins act as the ‘sorting hat’ of the type VI secretion system" and was chosen by Professor David Grainger.

In this paper, Wood and colleagues investigate how effector proteins are targeted to the type VI secretion system (T6SS). Working with Pseudomonas aeruginosa, they showed that a specific proline–alanine–alanine–arginine repeat (PAAR) protein is required to deliver a specific effector. This implies that entire networks of interactions, between PAAR proteins, effectors, and other components of the T6SS, ultimately determine specificity. Understanding these interactions will permit easier manipulation of T6SS for applications in biotechnology.


PAAR proteins act as the ‘sorting hat’ of the type VI secretion system

The type VI secretion system (T6SS) is a bacterial weapon, analogous to a molecular crossbow. It fires poisoned arrows into neighbouring bacteria or into other cells such as our own. Here, we discover a new toxin from a harmful bacterium, Pseudomonas aeruginosa, delivered by this T6SS crossbow and identify its antidote. We determine that the toxin is delivered not only by a specific arrow, but a specific arrowhead. Genetic engineering of this bacterium allowed us to show that the identity of the arrowhead controls which arrows are fired and thereby the nature of the toxins delivered by this weapon.

We spoke with corresponding author Professor Alain Filloux to find out more:

What is your institution and how long have you been there?

I joined Imperial College London in September 2007.

What is your research area?

My research field is molecular bacteriology and pathogenesis. The main questions we ask revolve around the molecular mechanisms that a bacterial pathogen such as Pseudomonas aeruginosa use to be virulent, to cause infection and be resistant to antimicrobials.

What inspired you to research this topic?

From very early on, I have been fascinated by the world of microbes and how much you can learn on the physiology of living cells by using bacteria as model organisms.

What is the most rewarding part of your research?

Rewards are discoveries and their valorisation. It's even more rewarding when discoveries are driven by students you trained in your laboratory as was the case with this paper which included three of my PhD students Tom Wood, Sophie Howard and Sarah Wettstadt.

To access the full paper, click here. Editor's Choice articles published in Microbiology are free to read.