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Published: 17 May, 2009

Umeå scientists map Listeria bacteria gene expression

NEWS In a new study published in the journal Nature, five researchers at Umeå University in collaboration with a French team at the Pasteur Institute in Paris, have displayed a detailed mapping of genes that the bacterium Listeria expressed under different environmental conditions.

Listeria monocytogenes causes several types of infections in humans, predominantly in persons with weak immune systems, and pregnant mothers. The bacteria are typically found in various foods, especially dairy products. After being absorbed orally in the body, it can pass from the gastrointestinal tract into the blood and lymphatic system. After growth in the liver and spleen, it can later spread to the brain or the placenta and cause deadly infections.

In the article published in Nature, a detailed study of the gene expression in Listeria monocytogenes was carried with a special technique (high-resolution tiling arrays), enabling a precise description of how different genes are activated or blocked in response to external influences. The team of scientists have studied the bacteria under various conditions, such as during growth in the digestive tract and in the blood system. The results suggest that Listeria monocytogenes uses several different types of regulating systems according to various environmental conditions. Suprisingly, several non-coding RNAs absent in the non-pathogenic species Listeria innocua exhibit the same expression patterns as the virulence genes. In essence, the article shows that the studied bacterium uses more complex regulatory mechanisms than previously thought.

Five of the study authors - Edmund Loh, Jonas Gripen Country, Teresa Tiensuu, Karolis Vaitkevicius and Jörgen Johansson (group leader) – work at the Department of Molecular Biology, Umeå University, and are also affiliated with the Laboratory for Molecular Infection Medicine Sweden (MIMS).

For more information, contact postdoctoral research fellow Jörgen Johansson, Department of Molecular Biology, Umeå UnivesityPhone: +46 (0)90-785 25 35
E-mail: jorgen.johansson@molbiol.umu.se

Reference: A Toledo-Aran, O Dussurget, G Nikitas, N Sesto, H Guet-Revillet, Balestrino D, E Loh, J Gripenberg Country, T Tiensuu, K Vaitkevicius, M Barthelemy, M Vergassola, MA Nahori, G Soubigou, B Regnault, JY Coppée, M Lecuit, J Johansson, P Cossart. The Listeria transcriptional landscape from saprophytism Thursday virulence Advance Online Publication (AOP)
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature08080.html