Dr Daniela Barillà

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Overview

The precise distribution of newly replicated genomes to progeny cells is crucial for stable transmission of genetic information. Bacteria and Archaea employ dedicated DNA segregation factors that drive and deliver low copy number plasmids and chromosomes to specific subcellular locations.

Segregation mechanisms of a multidrug resistance plasmid

One of the model systems under investigation is the multidrug resistance plasmid TP228 that replicates at low copy number in Escherichia coli. This mobile genetic element specifies resistance to a range of antibiotics, including tetracycline, streptomycin and sulphonamides. The plasmid harbours a partition cassette encoding two proteins that are crucial for plasmid inheritance: ParF, a ParA Walker-type ATPase, and ParG, a site-specific DNA-binding protein. We have employed multidisciplinary approaches, spanning from genetics to biochemistry, from cell biology to biophysics, to investigate the role and interactions of these proteins in mediating plasmid segregation. Two discoveries have made significant contributions to the field of bacterial genome segregation:

  • the observation that ParF assembles into higher-order structures [EMBO J 2005, 24:1453-1464]
  • the finding that ParG stimulates ParF ATP hydrolysis via an arginine finger- like motif in a fashion analogous to eukaryotic RasGAPs [Proc Natl Acad Sci USA 2007, 104: 1811-1816].

Structure of the ParF protein bound to the ATP analogue AMPPCP, one monomer is shown in blue-green and he other in red-orange.

ParF Structure

Recently we solved the three-dimensional structure of ParF [J Biol Chem 2012, 287: 26146-26154] http://www.jbc.org/content/287/31/26146.long. Crystal structures of the protein in different nucleotide-bound states suggest a mechanism underlying polymer formation. Discovering the mechanisms whereby multidrug resistance plasmids are inherited will ultimately help us to develop novel therapeutic agents to combat bacterial infections.

Genome segregation in thermophilic Archaea

Archaea are fascinating objects of investigation as they can thrive in very harsh environments thanks to molecular adaptations to a life pushed to extremes. Genome segregation in the archaea domain is virtually an uncharted territory. Two lines of research are currently being pursued, one focusing on mechanisms responsible for chromosome segregation in Sulfolobus solfataricus [Proc Natl Acad Sci USA 2012, 109: 3754-3759] and the other investigating the segregation of a low copy number plasmid in a different Sulfolobus species isolated from acidic hot springs in the island of Hokkaido, Japan. The toolkit for the stable inheritance of this plasmid is a unique three-component machine borrowing building blocks from bacteria and eukarya, including a CenpA-like histone. One of the proteins, AspA, binds to the centromere-like site, spreading on the DNA and building a superhelix template onto which the other two factors assemble to mediate plasmid segregation [Science 2015, 349: 1120-1124] http://www.sciencemag.org/content/349/6252/1120.


Structure of the AspA-DNA superhelix. The centrally bound dimer is shown in magenta and dimers spreading in the 5’ and 3’ directions are green and blue. The DNA helix is shown in yellow.

Daniela Barilla AspA-DNA superhelix

Research Group

NameStatusProject
Azhar Kabli

Postdoctoral Research Associate

Mechanisms of chromosome segregation in Archaea.

Gina Allison

PhD Student Assembly dynamics of the DNA segregation protein ParF.

Cecilia Pennica

PhD Student

Molecular interactions underpinning the segregation of the multidrug resistance plasmid TP228.

Iman Alnaqshabandy

PhD Student

Mechanisms and dynamics of the segregation of plasmid pB171.

Judith Hawkhead

Senior Research Technician

Structure-function analysis of chromosome segregation factors in Archaea.

Publications


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Dr Daniela Barilla

Contact details

Dr Daniela Barillà
Reader
Department of Biology (Area 10)
University of York
Heslington
York
YO10 5DD

Tel: 01904 328715