article

Researchers uncover tools used by predatory bacteria to escape unharmed from prey cell

Wednesday, 23 September 2020

Predatory bacteria, capable of invading and consuming harmful bugs such as E .coli and Salmonella, use a unique tool to help them escape the cell they have invaded without harming themselves, according to a new study.

Researchers at the Universities of Birmingham and Nottingham have identified a particular enzyme used by the bacteria to rupture the cell wall of its prey bacteria and exit without damaging its own cell wall. Their findings are published in Nature Communications.

The bacterium, called Bdellovibrio bacteriovorus, is important because the types of cells they attack – Gram negative bacteria – are responsible for many infections that are resistant to currently available antibiotics. This means predatory bacteria could have the potential to be harnessed as a therapy against these infections.

Discovering precisely how Bdellovibrio bacteriovorus succeeds in invading, and then escaping its prey cells is an important step in this process.

The enzyme they discovered seems like a well-known enzyme called a lysozyme- one of the earliest- ever studied enzymes and found in human tears and saliva; but this one has a twist where it has changed to do something surprising.

Bdellovibrio bacteriovorus is known for its ability to invade prey bacteria and stay inside the cell for a few hours, effectively eating the bacteria alive,” explains Dr Andrew Lovering, of the University of Birmingham’s School of Biosciences. “At the end of this process, the predator is able to break the prey open and escape. Because the walls of both the predator and prey cells are made of very similar molecules, we wanted to find out how the predator was able to cut the cell wall material of the prey cell and get out without damaging itself in the process.”

The team already knew part of the answer lay in an early action by the predator bacteria to remove a particular molecule, from the cell wall of the prey.  This created a ‘marker’ identifying the prey wall material as different to the predator. This  suggested subsequent action by a particular type of enzyme known as a lysozyme might be at work. Lysozymes are a family of enzymes which are known to play a role in the breakdown of cell walls of certain bacteria. This particular lysozyme had evolved and been changed in the predatory bacterium to take on the task of rupturing the uniquely modified cell wall to enable the escape to take place.

Identifying precisely which lysozyme had been diversified for this role was the result of painstaking work by PhD students Hannah Somers and Chris Harding, working with Swiss National Science Foundation Fellow Dr Simona Huwiler.

Dr Simona Huwiler

Professor Liz Sockett, from the University of Nottingham’s School of Life Sciences and  co-lead author of the paper, said: ”Checking the timing of when the Bdellovibrio used each of its lysozymes in predation, and hours at the microscope seeing what happened to prey-escape when each lysozyme was missing, gave us strong hunch which might be the important one for escape.”

“When we looked closely at the lysozyme it was clear we were on the right path,” says Dr Lovering. “It looked like a conventional lysozyme but with a warped active site, which meant it was unable to recognise the wall material  unless it had been modified and marked by the Bdellovibrio bacteria.”

The next step was to confirm that the lysozyme was only active against the modified cell wall and the team worked with Dr Patrick Moynihan, also in the School of Biosciences at the University of Birmingham, on tests to verify this.  This showed it to be a novel lysozyme with a different target to all those lysozymes previously studied in science.

Dr Simona Huwiler, in Professor Sockett’s lab then carried out a series of experiments with the predator bacteria showing clearly how adding this novel lysozyme  during the predation process led to the predator falling out from the prey cell early before finishing its meal. So the novel lysozyme is the key to exit.

LizandSimona
Understanding the mechanism and actions of this novel lysozyme may help us use it directly against pathogens which modify their own cell walls to resist the lysozymes in saliva and tears. It is is also an important step towards being able to use predatory bacteria themselves in new therapies against problematic bacteria.
Professor Liz Sockett

The research was funded by the Biotechnology and Biological Sciences Research Council and by a fellowship to Dr Huwiler from the Swiss National Science Foundation. Ongoing work is funded by the Wellcome Trust.

Story credits

More information is available from Professor Liz Sockett on Liz.Sockett@nottingham.ac.uk or Jane Icke, Media Relations Manager for the Faculty of Science at the University of Nottingham, on +44 (0)115 951 5751 or jane.icke@nottingham.ac.uk

 

janeicke
Jane Icke - Media Relations Manager Science
Email: jane.icke@nottingham.ac.uk
Phone: 0115 7486462
Location:

Notes to editors:

The University of Nottingham

Our academics can now be interviewed for broadcast via our Media Hub, which offers a Quicklink fixed camera and ISDN line facilities at Jubilee campus. For further information please contact a member of the Press Office on +44 (0)115 951 5798, email pressoffice@nottingham.ac.uk

For up to the minute media alerts, follow us on Twitter

The University of Nottingham is a research-intensive university with a proud heritage. Studying at the University of Nottingham is a life-changing experience, and we pride ourselves on unlocking the potential of our students. We have a pioneering spirit, expressed in the vision of our founder Sir Jesse Boot, which has seen us lead the way in establishing campuses in China and Malaysia - part of a globally connected network of education, research and industrial engagement. Ranked 18th in the UK by the QS World University Rankings 2023, the University’s state-of-the-art facilities and inclusive and disability sport provision is reflected in its crowning as The Times and Sunday Times Good University Guide Sports University of the Year twice in three years, most recently in 2021. We are ranked seventh for research power in the UK according to REF 2021. We have six beacons of research excellence helping to transform lives and change the world; we are also a major employer and industry partner - locally and globally. Alongside Nottingham Trent University, we lead the Universities for Nottingham initiative, a pioneering collaboration which brings together the combined strength and civic missions of Nottingham’s two world-class universities and is working with local communities and partners to aid recovery and renewal following the COVID-19 pandemic.

More news…

Media Relations - External Relations

The University of Nottingham
C Floor, Pope Building (Room C4)
University Park
Nottingham, NG7 2RD

telephone: +44 (0) 115 951 5798
email: pressoffice@nottingham.ac.uk