Publicação
Characterisation of a novel family of putative Glutamate Receptor-like interacting proteins in Arabidopsis thaliana
| Resumo: | CORNICHON proteins (CNI) form a conserved family of cargo receptors, found in almost all eukaryotes. Besides their most ancestral role as trafficking mediators of transmembrane proteins, some CNI homologs (CNIH) evolved specific interactions with ionotropic glutamate-receptors (iGluR) by being part of the channel complex, regulating iGluR’s gating properties at the membrane. Since Arabidopsis encodes five CNIHs and 20 glutamate receptor-like (GLR) proteins, the present work aimed to characterise AtCNIH’s function as well as to assess a putative GLR-CNIH interaction. The five AtCNIH genes present a similar genetic structure characterised by four exons with the 2nd and the 3rd very conserved in size, probably encoding for motifs with importance for AtCNIH’s function. Phylogenetically, AtCNIHs diverged into two different clusters, one sub-grouping AtCNIH2-5 with homologs of the most ancient plants and the other comprising AtCNIH1, which - strikingly - exclusively groups with angiosperm CNIHs, suggesting a divergent evolution within that plant division. Moreover, phenotypic analyses were carried out in many developmental stages of Arabidopsis. Seeds from cnih1 and cnih5 mutants showed a decreased size and weight, with repercussions on the germination rate. In roots, cnih mutants presented an impaired growth, except for cnih3, demonstrating that presumably all CNIHs play a role in root development. However, in ion imbalanced media cnih1 mutants showed not only the shortest roots but also a different growth profile, indicating the essential role of this isoform in roots. Furthermore, cnih mutants grown in short-day conditions showed a delay in flowering time. Subcellular localisation studies revealed that AtCNIHs are resident proteins of the ER. This localisation was also shown for homologs from other organisms, thereby being suggestive of a similar role for the plant CNIHs. As the GLR-CNIH interaction studies accomplished in this work did not allow conclusive interpretations, further experiments are needed to characterise their degree of interaction. |
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| Autores principais: | Nunes, Custódio de Oliveira, 1990- |
| Assunto: | Arabidopsis thaliana Biologia do desenvolvimento Embriologia vegetal Teses de mestrado - 2014 |
| Ano: | 2014 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | CORNICHON proteins (CNI) form a conserved family of cargo receptors, found in almost all eukaryotes. Besides their most ancestral role as trafficking mediators of transmembrane proteins, some CNI homologs (CNIH) evolved specific interactions with ionotropic glutamate-receptors (iGluR) by being part of the channel complex, regulating iGluR’s gating properties at the membrane. Since Arabidopsis encodes five CNIHs and 20 glutamate receptor-like (GLR) proteins, the present work aimed to characterise AtCNIH’s function as well as to assess a putative GLR-CNIH interaction. The five AtCNIH genes present a similar genetic structure characterised by four exons with the 2nd and the 3rd very conserved in size, probably encoding for motifs with importance for AtCNIH’s function. Phylogenetically, AtCNIHs diverged into two different clusters, one sub-grouping AtCNIH2-5 with homologs of the most ancient plants and the other comprising AtCNIH1, which - strikingly - exclusively groups with angiosperm CNIHs, suggesting a divergent evolution within that plant division. Moreover, phenotypic analyses were carried out in many developmental stages of Arabidopsis. Seeds from cnih1 and cnih5 mutants showed a decreased size and weight, with repercussions on the germination rate. In roots, cnih mutants presented an impaired growth, except for cnih3, demonstrating that presumably all CNIHs play a role in root development. However, in ion imbalanced media cnih1 mutants showed not only the shortest roots but also a different growth profile, indicating the essential role of this isoform in roots. Furthermore, cnih mutants grown in short-day conditions showed a delay in flowering time. Subcellular localisation studies revealed that AtCNIHs are resident proteins of the ER. This localisation was also shown for homologs from other organisms, thereby being suggestive of a similar role for the plant CNIHs. As the GLR-CNIH interaction studies accomplished in this work did not allow conclusive interpretations, further experiments are needed to characterise their degree of interaction. |
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