In fact, TALE, RipTAL, and BAT repeats can be mixed and matched to generate functional DNA-binding proteins with varying affinity.

TALEs from even closely related strains differ in the composition of repeats that make up their DNA binding domain.

[12] Based on similar domain structure and repeat sequences it was presumed that this gene and homologs in other Ralstonia strains would encode proteins with the same molecular properties as TALEs, including sequence-specific DNA binding.

[15] Whilst the DNA binding code of the core repeats is conserved with TALEs, RipTALs do not share the T-zero preference, instead they have a strict G-zero requirement.

[16] Several lines of evidence support the idea that RipTALs function as effector proteins, promoting bacterial growth or disease by manipulating the expression of plant genes.

[13] In addition a strain lacking its RipTAL was shown to grow slower inside eggplant leaf tissue than the wild type.

[19] This is expected if the RipTALs of different strains are adapted to target genes in specific host plants.

The publication of the genome of bacterial strain Paraburkholderia rhizoxinica HKI 454, in 2011 [20] led to the discovery of a set of TALE-like genes that differed considerably in nature from the TALEs and RipTALS.

The proteins encoded by these genes were studied for their DNA binding properties by two groups independently and named the Bats (Burkholderia TALE-likes; E5AV36) or BurrH.

Those domains are key to the functions of TALEs and RipTALs allowing them to infiltrate the plant nucleus and turn on gene expression.

What is clear is that they are not effector proteins secreted into plant cells to act as transcription factors, the biological role of TALEs and RipTALs.

In addition, Burkholderia TALE-likes have no T-zero requirement relaxing the constraints on DNA target selection.

However, few uses of Burkholderia TALE-likes as programmable DNA binding proteins have been published, outside of the original characterization publications.

The proteins encoded by these DNA sequences were therefore designated Marine Organism TALE-likes (MOrTLs) 1 and 2 (GenBank: ECG96325, EBN91409).

It is known only that they were found in two separate sea-water samples from the Gulf of Mexico and are likely to be bacteria based on size-exclusion before DNA sequencing.