A Simple Cipher Governs DNA Recognition by TAL Effectors

TLDR

TAL effectors from Xanthomonas bacteria manipulate plant gene regulation by delivering proteins into the nucleus, and recent studies have shown that the variable repeats in these proteins encode DNA‑binding specificity. Each TAL repeat recognizes a single DNA base pair through hypervariable amino acids, and assembling repeats with distinct hypervariable residues enables the design of effectors that target arbitrary DNA sequences.

Abstract

TAL Order Xanthomonas bacteria attack their plant hosts by delivering their own transcription-activator–like (TAL) proteins into the plant cell nucleus and alter the plant's gene regulation (see the Perspective by Voytas and Joung ). Moscou and Bogdanove (p. 1501 , published online 29 October: see the cover) and Boch et al. (p. 1509 , published online 29 October) have now discovered how the similar but not identical repeats in the TAL proteins encode the specificity needed for the proteins to find their targets. 1501 , published online 29 October: see the cover) and Boch et al. (p. 1509 , published online 29 October) have now discovered how the similar but not identical repeats in the TAL proteins encode the specificity needed for the proteins to find their targets. Each repeat is specific for one DNA base pair, a specificity encoded by hypervariable amino acid positions. Combining several repeats with different amino acids in the hypervariable positions allowed the production of new effectors that targeted new DNA sites.