Interkingdom Complementation Reveals Structural Conservation and Functional Divergence of 14-3-3 Proteins |
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| Authors: | Marco Lalle Flora Leptourgidou Serena Camerini Edoardo Pozio Efthimios M. C. Skoulakis |
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| Affiliation: | 1. Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy.; 2. Biomedical Sciences Research Centre “Alexander Fleming” Vari, Greece.; 3. Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy.; Russian Academy of Sciences, Institute for Biological Instrumentation, Russian Federation, |
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| Abstract: | The 14-3-3s are small acidic cytosolic proteins that interact with multiple clients and participate in essential cellular functions in all eukaryotes. Available structural and functional information about 14-3-3s is largely derived from higher eukaryotes, which contain multiple members of this protein family suggesting functional specialization. The exceptional sequence conservation among 14-3-3 family members from diverse species suggests a common ancestor for 14-3-3s, proposed to have been similar to modern 14-3-3ε isoforms. Structural features of the sole family member from the protozoan Giardia duodenalis (g14-3-3), are consistent with this hypothesis, but whether g14-3-3 is functionally homologous to the epsilon isoforms is unknown. We use inter-kingdom reciprocal functional complementation and biochemical methods to determine whether g14-3-3 is structurally and functionally homologous with members of the two 14-3-3 conservation groups of the metazoan Drosophila melanogaster. Our results indicate that although g14-3-3 is structurally homologous to D14-3-3ε, functionally it diverges presenting characteristics of other 14-3-3s. Given the basal position of Giardia in eukaryotic evolution, this finding is consistent with the hypothesis that 14-3-3ε isoforms are ancestral to other family members. |
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