Overview

Project Highlights:

  • Cutting-edge 3D chromosome reconstruction and “gene transplants” using CRISPR
  • Understanding the evolution of chromosomes of photosynthetic organisms
  • Redesigning bacterial chromosomes for efficient photosynthesis

Photoautotrophic bacteria (cyanobacteria) are responsible for over a quarter of oxygen produced on Earth. They are essential for maintenance of food webs and through endosymbiosis, led to the rise of all land plants. Yet our basic understanding of their cell biology is poor. This is problematic, when, for instance, attempting to use synthetic biology to rationally engineer photosynthetic cell factories (e.g. for biofuel production).

In general, bacteria organise their genomes in operons. Genes involved in certain processes are found close to one another in the genome to allow coordinate expression in response to external stimuli. The process of photosynthesis poses a huge demand on the cell. The continuous damage to the photosynthetic apparatus by light, results in the cell dedicating a large fraction of transcription and translation to making this apparatus de novo and targeting it to the site of photosynthesis, the thylakoid membrane. We might therefore expect that genes involved with photosynthesis to be arranged in operon like structures such that regulation is coordinated and not wasteful. In reality, photosynthesis genes are sparsely distributed across the genome. Why this is the case remains a mystery.

Recently, high-resolution electron microscope images of the interior of cyanobacterial cells has revealed a high concentration of ribosomes around the area of thylakoid membrane biogenesis (Figure 1A). Since bacteria complete transcription and translation almost simultaneously, and ribosomes centre on sites of thylakoid biogenesis, we pose the hypothesis that the 3D conformation of the chromosome means photosynthesis genes are orientated to this site. You will test this hypothesis using recently developed chromosome conformation mapping, “gene transplants” via CRISPR based mutagenesis and advanced confocal microscopy imaging. Your results will have implications for the evolution of phototrophy on Earth, and how we can generate more efficient photosynthetic cell factories.

 

(A) Concentration of ribosomes (grey) around thylakoid membranes (green). Images are from cryo-electron tomograms presented by [1]. (B) Methods to reconstruct the structure of bacterial chromosomes (

Methodology

You will use 3D chromosome structure reconstruction techniques [2]. You will couple this with CRISPR based engineering of the cyanobacterial chromosomes to relocate photosynthesis genes in the chromosome (“gene transplants”). Lastly, you will use fluorescent in-situ hybridisation and confocal microscopy to image the location of genes in the cell.

Training and Skills

This project offers numerous technical transferable skills. These include molecular cloning; CRISPR based mutagenesis and high throughout automation using robotics. In addition, you will use high-throughput sequencing (Illumina) and become expert in confocal microscopy.

Timeline

Year 1: Generate 3D maps of cyanobacterial chromosomes. Test whether light can affect these 3D maps.

Year 2: Use fluorescent in-situ hybridisation and fluorescently labelled proteins to localise genes within the cell

Year 3: Perform “chromosome transplants” of key photosynthesis genes and test whether genome location affects the ability of the cell to perform photosynthesis.

Partners and collaboration (including CASE)

The supervisors are world-leading experts in cyanobacterial cell biology, as evidenced by regularly publishing in high profile interdisciplinary journals (e.g. Proc. Natl. Acad. Sci. USA, Current Biology) and field specific high impact journals (e.g. The ISME Journal). The supervisors have combined experience of >25 years. You will belong to a larger group of environmental microbiologists in the department of life sciences’ environment theme. (https://warwick.ac.uk/fac/sci/lifesci/research/envbiosci/). These groups occupy a large shared lab area and as such, there is continuous collaborations and opportunities for career development within the theme. Current research in the groups is funded by NERC and generous start-up award to Dr. Puxty.

Further Details

Applicants from the UK or the EU are eligible. Applicants should hold a BSc and/or MSc degree in relevant subjects. Informal enquires can be made to Dr Richard Puxty (r.puxty@warwick.ac.uk) or Prof. David Scanlan (d.j.scanlan@warwick.ac.uk). Details of how to apply can be found at https://warwick.ac.uk/fac/sci/lifesci/study/pgr/studentships/nerc-centa/