Two independent teams of researchers - one from the Martin Luther University Halle-Wittenberg in Germany and the other from the Iowa State University, have discovered how a group of proteins from the plant pathogenic bacterium Xanthomonas interact with DNA in their plant host cell. The teams led by Jens Boch and Adam Bogdanove described how the virulence factors TAL (short for transcription activator-like effectors) bind to specific portions of the plant DNA and manipulate plant gene functions in ways that benefit the pathogen.

Scientists have known that TAL binds to the DNA via a central domain of 34 amino acid repeats. Now Boch and Bogdanove and their teams showed independently that a pair of amino acid residues in each repeat recognizes one base pair in the target DNA "with no apparent context dependence." "This simple relationship allows us to predict where a TAL effector will bind, and what genes it will activate. It also makes it likely that we can custom engineer TAL effectors to bind to virtually any DNA sequence," said Bogdanove.

The discovery of the "cipher" that governs DNA recognition by TAL effectors opens promising applications for research and biotechnology. For instance, TAL binding sites might be attached to disease resistance genes so they are activated upon infection.

The papers published by Science are available at   http://dx.doi.org/10.1126/science.1178811 dan http://dx.doi.org/10.1126/science.1178817 For more information, read the original story at   http://www.news.iastate.edu/news/2009/nov/bogdanove