Modes of TAL effector-mediated repression.
Engineered transcription activator-like effectors, or TALEs, have emerged as a new class of designer DNA-binding proteins. Their DNA recognition sites can be specified with great flexibility. When fused to appropriate transcriptional regulatory domains, they can serve as designer transcription factors, modulating the activity of targeted promoters. We created tet operator (tetO)-specific TALEs (tetTALEs), with an identical DNA-binding site as the Tet repressor (TetR) and the TetR-based transcription factors that are extensively used in eukaryotic transcriptional control systems. Different constellations of tetTALEs and tetO modified chromosomal transcription units were analyzed for their efficacy in mammalian cells. We find that tetTALE-silencers can entirely abrogate expression from the strong human EF1α promoter when binding upstream of the transcriptional control sequence. Remarkably, the DNA-binding domain of tetTALE alone can effectively counteract trans-activation mediated by the potent tettrans-activator and also directly interfere with RNA polymerase II transcription initiation from the strong CMV promoter. Our results demonstrate that TALEs can act as highly versatile tools in genetic engineering, serving as trans-activators, trans-silencers and also competitive repressors.
Helmholtz-Zentrum Geesthacht (HZG), Institute of Biomaterial Science, Teltow 14513, Germany Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Föhrer Strasse 15, 13353 Berlin, Germany.
Jeannette
J
Werner
Helmholtz-Zentrum Geesthacht (HZG), Institute of Biomaterial Science, Teltow 14513, Germany Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Föhrer Strasse 15, 13353 Berlin, Germany manfred.gossen@charite.de.
Manfred
M
Gossen
D001665:Binding Sites; D001667:Binding, Competitive; D002460:Cell Line; D003587:Cytomegalovirus / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D011401:Promoter Regions, Genetic; D015202:Protein Engineering; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism
D012097:Repressor Proteins; D015534:Trans-Activators; C034811:tetracycline resistance-encoding transposon repressor protein