IAL   21557
INSTITUTO DE AGROBIOTECNOLOGIA DEL LITORAL
Unidad Ejecutora - UE
artículos
Título:
Plant homeodomain-leucine zipper I transcription factors exhibit different functional AHA motifs that selectively interact with TBP or/and TFIIB
Autor/es:
CAPELLA, MATIAS; RÉ DELFINA A.,; ARCE AGUSTIN; CHAN RAQUEL
Revista:
PLANT CELL REPORTS
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2014 p. 1 - 13
ISSN:
0721-7714
Resumen:
Homeodomain-leucine zipper proteins are transcriptionfactors unique to plants, classified in four subfamilies.Subfamily I members have been mainlyassociated to abiotic stress responses. Several ones havebeen characterized using knockout or overexpressorsplants, indicating that they take part in different signaltransduction pathways even when their expression patternsare similar and they bind the same DNA sequence. Abioinformatic analysis has revealed the existence of conservedmotifs outside the HD-Zip domain, includingtransactivation AHA motifs. Here, we demonstrate thatthese putative activation motifs are functional. Fourmembers of the Arabidopsis family were chosen: AtHB1,AtHB7, AtHB12 and AtHB13. All of them exhibitedactivation activity in yeast and in plants but with differentdegrees. The protein segment necessary for such activationwas different for these four transcription factors as well asthe role of the tryptophans they present. When interactionwith components of the basal transcription machinery wastested, AtHB1 was able to interact with TBP, AtHB12interacted with TFIIB, AtHB7 interacted with both, TBPand TFIIB while AtHB13 showed weak interactions withany of them, in yeast two-hybrid as well as in pull-downassays. Transient transformation of Arabidopsis seedlingsconfirmed the activation capacity and specificity of thesetranscription factors and showed some differences with theresults obtained in yeast. In conclusion, the differentialactivation functionality of these transcription factors addsan important level of functional divergence of these proteins,and together with their expression patterns, thesedifferences could explain, at least in part, their functionaldivergence.