Sweet as can be: how E. coli gets ahead
Posted on 12 November 2009
Bacteria have evolved many related transporters to allow them to exploit every possible potential source of nutrient in their environment
Dr Gavin Thomas
Microbes are well-known for their ability to grow in demanding and nutritionally poor environments, which has allowed them to colonise some of the most remote places on the planet. Bacteria living in theoretically nutrient-rich environments like the mammalian intestine face similar challenges due to intense competition between bacterial species in the intestine for the finite amount of available food.
Researchers led by Dr Gavin Thomas in the University’s Department of Biology discovered that a protein present in the intestinal bacterium Escherichia coli was a unique sugar transporter.
Common sugars like glucose form a cyclic structure called a ‘pyranose’ when dissolved in water. All transporters for glucose recognise the pyranose form. But, for sugars such as galactose, which is commonly found in dairy produce, around 10 per cent is found in a different ring form called a ‘furanose’.
Initial work on the unknown E. coli transporter by Dr Thomas’s team suggested that it was a galactose transporter. The researchers knew that E. coli has a galactopyranose transporter already, so why should the bacterium have evolved another system to do exactly the same thing?
The answer to the problem was discovered when researchers led by Professor Keith Wilson in the York Structural Biology Laboratory solved the 3D structure of the protein, revealing that it was bound to the rarer furanose form of galactose. Experiments by Dr Jennifer Potts in the University’s Centre for Magnetic Resonance confirmed that the transporter was the first biological example to recognise furanose over pyranose forms.
Dr Thomas said: “The picture that emerges is that bacteria have evolved many related transporters to allow them to exploit every possible potential source of nutrient in their environment. Being able to use the extra 10 per cent of galactose available in the gut appears a trivial adaptation. But it is exactly the small change required to allow E. coli to grow a little bit faster when galactose is present in the gut, and so persist at the expense of other species of bacteria.”
The work was funded through a Biotechnology and Biological Sciences Research Council quota studentship to Dr Richard Horler in the laboratory of Dr Thomas. The research involved Dr Axel Muller, from the laboratory of Professor Wilson, and NMR expertise from David Williamson and Dr Potts. The work was published in the Journal of Biological Chemistry.
ENDS
Notes to editors:
- The York Structural Biology Laboratory (YSBL) uses and develops methods to determine, analyse and exploit the structure of proteins and their complexes with other molecules. The research provides insights into biological function and finds application in drug discovery and the exploitation of enzymes as biocatalysts.
- The University of York’s Department of Biology is one of the leading centres for biological teaching and research in the UK. In the 2008 Research Assessment Exercise, it was ranked equal first among broad spectrum bioscience departments in the UK for quality that was judged to be world-leading. The Department both teaches degree courses and undertakes research across the whole spectrum of modern Biology, from molecular genetics and biochemistry to ecology. Its biomedical research includes an Immunology and Infection Unit (jointly with the Hull York Medical School), work on infertility and three research professors funded by Yorkshire Cancer Research and York Against Cancer.
- The Department of Chemistry at the University of York has an excellent reputation for both teaching and research. Its research, covering all aspects of modern chemistry, was rated extremely highly in the 2008 Research Assessment Exercise. It has around 50 full-time members of staff including many winners of international prizes, over 460 undergraduate students, approximately 150 graduates and 80 research fellows. Its laboratories were recently extended and modernised. In 2007. the chemistry department at York was the first academic department in the UK to be given a gold award from the Athena SWAN Charter for Women in Science. These awards are granted in recognition of excellence in science, engineering and technology employment in higher education in relation to supporting women in science.
- The Biotechnology and Biological Sciences Research Council (BBSRC) is the UK funding agency for research in the life sciences. Sponsored by Government, BBSRC annually invests around £420 million in a wide range of research that makes a significant contribution to the quality of life for UK citizens and supports a number of important industrial stakeholders including the agriculture, food, chemical, healthcare and pharmaceutical sectors. BBSRC carries out its mission by funding internationally competitive research, providing training in the biosciences, fostering opportunities for knowledge transfer and innovation and promoting interaction with the public and other stakeholders on issues of scientific interest in universities, centres and institutes.
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