TAL effector

TAL effector
TAL (transcription activator-like) effectors (often referred to as TALEs) are proteins secreted by Xanthomonas bacteria when entering a plant cell. They manipulate the host cell by switching on certain genes that make the plant cell more susceptible to infection.  TALE subunits bind to the nucleotides of DNA in a 1:1 ratio, and each subunit has a pair of amino acids that is specific to a single DNA base.  This enables the TALEs to recognize specific DNA sequences and activate them.

These proteins are interesting to researchers both for their role in disease of important crop species and the relative ease of retargeting them to bind new DNA sequences.

Reference:
http://en.wikipedia.org/wiki/TAL_effector
Animation rendered from PDB file 3UGM with qutemol.
http://www.rcsb.org/pdb/explore/explore.do?structureId=3UGM
http://qutemol.sourceforge.net/