Abstract.
Similar to heat-stress transcription factors (HSFs) from non-plant sources, HSFA1 and HSFA2 from tomato (Lycopersicon esculentum Mill) contain two conserved clusters of basic amino acid residues (K/R1 and K/R2) which might serve as nuclear localization signal (NLS) motifs. Mutation of either one of them and functional testing of the corresponding proteins in a transient expression assay using tobacco (Nicotiana plumbaginifolia L.) protoplasts gave the following results. Whereas K/R1, positioned in all HSFs at the C-terminus of the DNA-binding domain, had no influence on nuclear import, the K/R1 mutants were impaired in their interaction with the DNA (band-shift assays). In contrast to this, mutants of the K/R2 motif, found 15–20 amino acid residues C-terminal of the oligomerization domain (HR-A/B region), had wild-type activity in DNA-binding but were defective in nuclear import. Thus, for the related tomato HSFA1 and HSFA2 the K/R2 cluster represents the only NLS motif, and in this function it cannot be replaced by K/R1.
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Received: 16 August 1996 / Accepted: 30 December 1996
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Lyck, R., Harmening, U., Höhfeld, I. et al. Intracellular distribution and identification of the nuclear localization signals of two plant heat-stress transcription factors. Planta 202, 117–125 (1997). https://doi.org/10.1007/s004250050110
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DOI: https://doi.org/10.1007/s004250050110