What is "tale-likes"

Transcription Activator Like Effector Likes (TALE-likes) are a group of bacterial DNA binding proteins named for the first and still best studied group, the TALEs of Xanthomonas bacteria. TALEs are important factors in the plant diseases caused by Xanthomonas bacteria, but are known primarily for their role in biotechnology as programmable DNA binding proteins, particularly in the context of TALE nucleases. TALE-likes have additionally been found in many strains of the Ralstonia solanacearum bacterial species complex, in Burkholderia rhizoxinica strain HKI 454, and in two unknown marine bacteria. Whether or not all these proteins from a single phylogenetic grouping is as yet unclear.

The unifying feature of the TALE-likes are their tandem arrays of DNA binding repeats. These repeats are, with few exceptions, 33-35 amino acids in length, and composed of two alpha-helices on either side of a flexible loop containing the DNA base binding residues and with neighbouring repeats joined by flexible linker loops. Evidence for this common structure comes in part from solved crystal structures of TALEs and a Burkholderia TALE-like, but also from the conservation of the code that all TALE-likes use to recognise DNA-sequences.