TCD Researchers Shed Light on Genetic Transfer Between Cells

Posted on: 26 February 2008

Antibiotic resistance threatens to become a major problem in the next decades, with MRSA already a household name.  

Important research led by Trinity College Dublin’s Professor Martin Hegner published on February 26, 2008 in the internationally peer-reviewed biological science journal PLoS Biology, sheds light on the mechanism by which bacteria transfer DNA to other cells, a process which can allow resistance to jump between species of bacteria.

Bacteria transfer DNA to other bacteria via a process called ‘conjugation’. One bacterium injects DNA into another, and that DNA can then become part of the recipient’s genome, which will be passed on to all clones that come from that cell.  This means that a beneficial mutation – such as the ability to digest an antibiotic – that occurs in one cell can be passed on to other unmutated bacteria nearby.

It has always been thought that the donor cell was the important party in this process and that the recipient bacterium was passive; that the DNA was pumped across by the donor.  However, the work led by TCD’s Professor Martin Hegner, a Principal Investigator at TCD’s nanoscience research centre, CRANN, and Professor in the School of Physics, with contributions from colleagues in Ireland, Switzerland and America, shows that the presence of specific proteins in the recipient play a key role in the import process.

The researchers studied a bacterium called Agrobacterium tumefaciens, which infects plant cells.  As part of the infection process, the bacterium injects DNA into the plant, making it an excellent model of conjugation.  Before DNA transfer, the bacterium transports proteins, including the DNA binding protein VirE2, into the plant.

VirE2 then plays a crucial role in DNA transfer.  It binds to the beginning of the DNA strand and forces it to assume a tightly organised helical structure, causing the rest of the strand to be pulled into the host cell.  The energy for this process all comes from the energy released by VirE2 binding to the DNA, rather then from any external source, or the donor cell.

Notes to the editor:

PLoS Biology is ranked as the most highly cited general biology journal with an impact factor of about 15.

CRANN, the Centre for Research on Adaptive Nanostructures and Nanodevices, is Ireland ‘s first purpose built nanoscience research centre, housed in TCD’s Naughton Institute.  CRANN’s mission is to deliver world class research and innovation in nanoscience and nanotechnology, of value both to its industry partners and to Ireland .