Tell Me a Tale of TALEs

Pathogenic bacteria of the Xanthomonas and Ralstonia genus have developed resourceful strategies creating a favorable environment to multiply and colonize their host plants. One of these strategies involves the secretion and translocation of several families of effector proteins into the host cell. The transcription activator-like effector (TALE) family forms a subset of proteins involved in the direct modulation of host gene expression. TALEs include a number of tandem 34-amino acid repeats in their central part, where specific residues variable in two adjacent positions determine DNA-binding in the host genome. The specificity of this binding and its predictable nature make TALEs a revolutionary tool for gene editing, functional analysis, modification of target gene expression, and directed mutagenesis. Several examples have been reported in higher organisms as diverse as plants, Drosophila, zebrafish, mouse, and even human cells. Here, we summarize the functions of TALEs in their natural context and the biotechnological perspectives of their use.