Análise da família das proteínas PAM2-like em soja: divergência funcional da subfamília das ERD15-like

• Autor(a) principal: Silva, Lucas Araújo Castro e
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2470
• topic: Proteínas - Análises; Soja; Arroz; ERD15; PAM2; Plantas - Estresse hídrico; Proteins - analysis; Soybeans; Rice; ERD15; PAM2; Plants - Water stress; CNPQ::CIENCIAS BIOLOGICAS::BIOQUIMICA::BIOLOGIA MOLECULAR

The PAM2 motif is largely distributed in eukaryotic proteins and was initially identified as a binding site for poly (A) binding proteins (PABP), which play a role in RNA metabolism. Despite the PAM2 motif relevance, a comprehensive analysis of its occurrence in proteins of the plant kingdom is still absent. In the present study, the PAM2-like protein family was phylogenetically characterized in Arabidopsis, soybean and rice. Totally, 19 PAM2-like sequences were identified in the Arabidopsis genome, while 31 members of the family were found in soybean and 22 members in rice. The PAM2-like family was subdivided in 7 subfamilies (A-G) based on the conservation of the sequences and in the structure of the motifs. Among them, the ERD15-like subfamily, whose name derives from the ERD15 (Early Responsive to Dehydration 15) Arabidopsis protein, originally identified by its rapid induction in response to dehydration, was characterized extensively, concerning its phylogeny, dehydration responsiveness and cellular function. Microarray data from stressed plants shows that both members of the ERD15-like subfamily in Arabidopsis, AtERD15 (AT2G41430) e AtERL15 (AT4G14270), are responsive to drought. The drought response profile of 4 of the 6 soybean ERD15-like subfamily members was also investigated. It was observed that the pair Glyma14g05980 and Glyma02g42860 is continuously induced as the stress progress, whereas the pair Glyma11g20940 and Glyma04g28560 is initially induced, but has a reduction on its expression level when the stress becomes more severe, indicating a possible functional divergence in the ERD15-like subfamily. The superexpression and the suppression of the AtERD15 gene were evaluated regarding to sensibility to ABA and tolerance to drought. A correlation between AtERD15 (AT2G41430) expression level and the germination rate of seeds in the presence of the phytohormone ABA was observed. Opposingly, a negative correlation was observed for the level of AtERD15 transcript and the root growth in plants stressed by PEG, as well as for the drought stress tolerance. The soybean, GmERD15-like (Glyma02g42860), and rice, OsERD15-like (Os07g46670), homologs shown partial phenotype complementation for ABA susceptibility during germination, as presented by AtERD15, but, on the contrary, promoted increased drought tolerance on stressed plants. Collectively, these results imply that the members of the ERD15-like family diverge in function. Under normal conditions, the proteins AtERD15, GmERD15-like and OsERD15-like are localized in the cytoplasm. Nonetheless, under osmotic stress, the subcellular localization profile of these proteins is modified, as they increase their concentration around the nucleus. The OsERD15-like protein (Os07g46670) was translocated to the nucleus under osmotic stress conditions. Under transient expression in tobacco leaves, the three proteins exhibited the same localization pattern, being present in the cytoplasm as well as in the nucleus, except in the nucleolus. Finally, it was demonstrated that the protein GmERD15-like (Glyma02g42860) is capable of binding to the promoters of the genes CDC2 (Glyma06g17640) and F-Box (Glyma13g43730) and that the superexpression of GmERD15-like in soybean protoplasts led the induction of both genes, in addition to DNAJ (Glyma14g31810). CDC2, DNAJ and F-Box are all induced by drought. These results indicate that GmERD15-like controls a selected group of genes induced by hydric stress.