Repeat 1 of TAL effectors affects target specificity for the base at position zero.
Bottom Line: AvrBs3, the founding member of the Xanthomonas transcription-activator-like effectors (TALEs), is translocated into the plant cell where it localizes to the nucleus and acts as transcription factor.T0 and W232 appear to be particularly important if the RVD of the first repeat is HD ('rep1 effect').Our findings provide novel insights into the mechanism of T0 recognition by TALE proteins and are important for TALE-based biotechnological applications.
Affiliation: Department of Genetics, Martin Luther University, Weinbergweg 10, 06120 Halle (Saale), Germany firstname.lastname@example.org.Show MeSH
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Mentions: Previously, it was suggested that the NTRs of TALEs serve as nucleation site for the DNA interaction (9,24). To integrate our data we propose the following model (Figure 7). TALEs may slide along the DNA scanning for the target sequence. Once the target sequence is reached, specific contacts between the canonical repeats and nucleobases occur from 5′ to 3′ and allow the repeats to compress (8,9,24). Taking this idea into account we hypothesize that the W232-T0 interaction facilitates the specific interaction between canonical repeats and target nucleobases which may be more crucial if an HD1 contact to C1 needs to be established (Figure 7). We can only speculate about the strong dependency of TALEs with HD1 on T0 and W232. One explanation could be that the amine group of cytosine targeted by HD is more distant from the sugar phosphate backbone than N7 of guanine and adenine or the methyl group of thymine targeted by other RVDs (Supplementary Figure S10). In addition, HD is the only RVD which accepts the hydrogen bond from the base, whereas others donate hydrogen bonds to the base or interact with the base via van der Waals forces (Supplementary Figure S10) (8,10,26).
Affiliation: Department of Genetics, Martin Luther University, Weinbergweg 10, 06120 Halle (Saale), Germany email@example.com.