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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Uncharacterized conserved motifs outside the HD-Zip domain in HD-Zip subfamily I transcription factors; a potential source of functional diversity | Arce et al. BMC Plant Biology 2011 11 42 http www.biomedcentral.com 1471-2229 11 42 BMC Plant Biology RESEARCH ARTICLE Open Access Uncharacterized conserved motifs outside the HD-Zip domain in HD-Zip subfamily I transcription factors a potential source of functional diversity Agustin L Arce Jesica Raineri Matias Capella Julieta V Cabello Raquel L Chan Abstract Background Plant HD-Zip transcription factors are modular proteins in which a homeodomain is associated to a leucine zipper. Of the four subfamilies in which they are divided the tested members from subfamily I bind in vitro the same pseudopalindromic sequence CAAT A T ATTG and among them several exhibit similar expression patterns. However most experiments in which HD-Zip I proteins were over or ectopically expressed under the control of the constitutive promoter 35S CaMV resulted in transgenic plants with clearly different phenotypes. Aiming to elucidate the structural mechanisms underlying such observation and taking advantage of the increasing information in databases of sequences from diverse plant species an in silico analysis was performed. In addition some of the results were also experimentally supported. Results A phylogenetic tree of 178 HD-Zip I proteins together with the sequence conservation presented outside the HD-Zip domains allowed the distinction of six groups of proteins. A motif-discovery approach enabled the recognition of an activation domain in the carboxy-terminal regions CTRs and some putative regulatory mechanisms acting in the amino-terminal regions NTRs and CTRs involving sumoylation and phosphorylation. A yeast one-hybrid experiment demonstrated that the activation activity of ATHB1 a member of one of the groups is located in its CTR. Chimerical constructs were performed combining the HD-Zip domain of one member with the CTR of another and transgenic plants were obtained with these constructs. The phenotype of the chimerical transgenic plants was similar to the observed in .
