Andrew FentonDr Andrew Fenton

Research Fellow


Tel:0114 222 2832
Email: a.k.fenton@sheffield.ac.uk

Research

Research Precis

Fig1

Work in my lab focuses on molecular mechanisms governing bacterial cell growth and division within the host environment. We study the ellipsoid-shaped model organism and human pathogen Streptococcus pneumoniae.

Pneumonia and meningitis are leading causes of death in the world. These diseases are caused by a variety of bacteria but are commonly caused by invasive S. pneumoniae. How these bacteria grow and divide inside their hosts is fundamental to our understanding of these conditions. My lab focuses on S. pneumoniae growth and division processes. Specifically, how the process of cell wall biosynthesis is governed and coordinated to maintain the cell shape and integrity as the cells grow and divide.

As S. pneumoniae cell growth takes place exclusively within the human host, we study the cell host-cell interactions to provide context of cell growth processes. We study how S. pneumoniae cells adapt to environmental changes within hosts, resists clearance by the immune system and copes with antibiotic challenges.

We use genetic screens, biochemical assays and epifluorescence microscopy to advance our understanding of the molecular mechanisms behind these processes.

Identification of a new cell wall biogenesis factor CozE using Tn-seq

Fig2

Our recent work has utilised a genetic screening technique called Tn-seq 1-3 to identify a new cell wall assembly factor: CozE. Broadly, the Tn-seq technique starts out with large populations of bacteria, each containing an individual gene inactivation. A selective pressure is applied to this population killing some of the more sensitised members. Next, all surviving members are sequenced and their individual gene inactivation is identified (Figure 1A). In this study, we exploited a known genetic relationship between two cell wall biosynthetic factors, PBP1a and PBP2a, to screen for new genes involved in the regulation of these enzymes. Examples of Tn-seq insertion profiles generated from this work are shown in Figure 1B. These insertion profiles revealed a novel cell wall biogenesis regulator in bacteria, which we named CozE for Coordinator Of Zonal Elongation.

CozE is essential for coordinated cell wall synthesis

Most bacterial cells are surrounded by a cellular exoskeleton called the cell wall. This structure gives the cells their shape and protects them from osmotic lysis. Our Tn-seq study identified the membrane protein CozE, which is essential for coordinated cell wall synthesis in S. pneumoniae (Figure 2A). The cell wall of S. pneumoniae is synthesised in a highly regulated manner involving the action of many enzymes. Removing CozE from S. pneumoniae cells effectively shatters this machinery into its composite pieces, dispersing them throughout the cell surface. Surprisingly, the PBP1a component of the machine appears to keep on working. Like an assembly line out of control, PBP1a synthesises new cell wall seemingly all over the place, inserting new material in inappropriate places. The cells are unable to cope with the aberrant synthesis, which makes them swell and eventually lyse (Figure 2B). Our current work focuses on understanding this rogue cell wall synthesis activity further to see if we can ultimately exploit it for future therapies.

For more information on CozE please read our paper: CozE is a member of the MreCD complex that directs cell elongation in Streptococcus pneumoniae.

Fig 3

MacP is required for PBP-driven cell wall synthesis

In order to construct a stable cell wall it is important for bacteria to regulate the function of the cell wall building enzymes. Our Tn-seq study identified the membrane protein MacP, which is a protein essential for the function of cell wall synthesis enzyme PBP2A in S. pneumoniae (Figure 3A,B). A deeper study of MacP function identified new signalling pathways that bacterial cells use to govern cell wall building processes. In this case, MacP phosphorylation acts as a switch that drives cell wall synthesis. Removing or preventing the MacP biological ‘switch’ inhibits growth and cells wither and burst (Figure 3C). This new type of cell wall regulation links growth to wider cell signalling pathways. How the MacP protein operates and what biological signals trigger the function of the cell wall building machines remains an open question for future study.

For more information on MacP, please read: Phosphorylation-dependent activation of the cell wall synthase PBP2a in Streptococcus pneumoniae by MacP



Research Keywords

Pneumonia, Streptococcus pneumoniae, host-pathogen interactions, antibiotic resistance, deep sequencing, cell division, cell wall, genetics, epifluorescence microscopy, time-lapse microscopy.


References

1. van Opijnen, T., Bodi, K. L. & Camilli, A. Tn-seq: high-throughput parallel sequencing for fitness and genetic interaction studies in microorganisms. Nat. Methods 6, 767–72 (2009).
2. Gawronski, J. D., Wong, S. M. S., Giannoukos, G., Ward, D. V & Akerley, B. J. Tracking insertion mutants within libraries by deep sequencing and a genome-wide screen for Haemophilus genes required in the lung. Proc. Natl. Acad. Sci. U. S. A. 106, 16422–16427 (2009)
3. Langridge, G. C. et al. Simultaneous assay of every Salmonella typhi gene using one million transposon mutants. Genome Res. 19, 2308–2316 (2009).
4. Fenton, A. K., El Mortaji, L., Lau, D. T. C., Rudner, D. Z. &Bernhardt, T.G. CozE is a member of the MreCD complex that directs cell elongation in Streptococcus pneumoniae. Nat. Microbiol. 2, 16237 (2016).
5. Fenton, A.K., Manuse, S., Flores-Kim, J., Garcia, P.S., Mercy, C., Grangeasse, C., Bernhardt, T.G., Rudner, D.Z. Phosphorylation-dependent activation of the cell wall synthase PBP2a in Streptococcus pneumoniae by MacP. PNAS. 115(11), 2812-2817 (2018)

Teaching

Level 1 Modules

MBB163 Microbiology 

Career History

Career History

  • 2016 - present: Florey Institute Research Fellow, Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, UK.
  • 2013 – 2016: Postdoctoral Fellow, Harvard Medical School, Boston, USA.
  • 2010 – 2013: Research Associate, Centre for Bacterial Cell Biology, Newcastle University, Newcastle, UK.
  • 2006 – 2010: PhD, Institute of Genetics, The University of Nottingham, Nottingham, UK.
About

About

I started my lab in MBB at the Florey Institute in December 2016. Before coming to Sheffield, my post-doctoral training took me to Harvard Medical School, where I discovered my love for Streptococcus pneumoniae. This was a jointly supervised project in the labs of both Tom Bernhardt and David Rudner where I learned the deep sequencing and genetic approaches which I now apply in my lab.

Between 2010 and 2013, I worked in the Centre for Bacterial Cell Biology in Newcastle with Kenn Gerdes (now at the University of Copenhagen). Here I learned how to work on proteins in depth and drive towards understanding molecular mechanisms of biological processes. My work focused mainly on the actin-like protein and major cell wall coordination factor MreB.
I completed a PhD in 2010 studying the predatory bacterium Bdellovibrio bacteriovorus in Liz Sockett’s lab. Predatory bacteria are fascinating and a lot of fun; here I learned how to be a scientist and the basics of a method very dear to me: time-lapse and florescence microscopy.

Things that make me happy are science (on good days), gaming, travelling and coffee. I tweet under the handle @AndrewKFenton.

Joining the Lab

Joining the Lab.

If you are interested in joining the team, please contact me at: a.k.fenton@sheffield.ac.uk

Postdoctoral Fellowships

Postdocs who wish to apply for fellowships to join the team are welcome. Please contact me to discuss project ideas.

Project students and Internships

Students wishing to apply for summer internships are welcome and should send me a CV and a letter describing their interests, motivations and research experience.


Publications

Journal articles

Chapters