RESUMO
Brugia malayi is a parasitic nematode that causes lymphatic filariasis in humans. Here the solution structure of the forkhead DNA binding domain of Brugia malayi DAF-16a, a putative ortholog of Caenorhabditis elegans DAF-16, is reported. It is believed to be the first structure of a forkhead or winged helix domain from an invertebrate. C. elegans DAF-16 is involved in the insulin/IGF-I signaling pathway and helps control metabolism, longevity, and development. Conservation of sequence and structure with human FOXO proteins suggests that B. malayi DAF-16a is a member of the FOXO family of forkhead proteins.
Assuntos
Brugia Malayi/metabolismo , DNA/química , Fatores de Transcrição Forkhead/química , Proteínas de Helminto/química , Modelos Moleculares , Fragmentos de Peptídeos/química , Sequência de Aminoácidos , Animais , Sítios de Ligação , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/metabolismo , Sequência Conservada , DNA/metabolismo , Ensaio de Desvio de Mobilidade Eletroforética , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Proteínas de Helminto/genética , Proteínas de Helminto/metabolismo , Dados de Sequência Molecular , Peso Molecular , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Conformação Proteica , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Elementos de Resposta , Alinhamento de Sequência , SolubilidadeRESUMO
The 26S proteasome is an essential multicatalytic protease complex that degrades a wide range of intracellular proteins, especially those modified with ubiquitin. Arabidopsis thaliana and other plants use pairs of genes to encode most of the core subunits, with both of the isoforms often incorporated into the mature complex. Here, we show that the gene pair encoding the regulatory particle non-ATPase subunit (RPN5) has a unique role in proteasome function and Arabidopsis development. Homozygous rpn5a rpn5b mutants could not be generated due to a defect in male gametogenesis. While single rpn5b mutants appear wild-type, single rpn5a mutants display a host of morphogenic defects, including abnormal embryogenesis, partially deetiolated development in the dark, a severely dwarfed phenotype when grown in the light, and infertility. Proteasome complexes missing RPN5a are less stable in vitro, suggesting that some of the rpn5a defects are caused by altered complex integrity. The rpn5a phenotype could be rescued by expression of either RPN5a or RPN5b, indicating functional redundancy. However, abnormal phenotypes generated by overexpression implied that paralog-specific functions also exist. Collectively, the data point to a specific role for RPN5 in the plant 26S proteasome and suggest that its two paralogous genes in Arabidopsis have both redundant and unique roles in development.
