RESUMO
Cytokinesis, the final step of cell division, usually ends with the abscission of the two daughter cells. In some tissues, however, daughter cells never completely separate and remain interconnected by intercellular bridges or ring canals. In this paper, we report the identification and analysis of a novel ring canal component, Nessun Dorma (Nesd), isolated as an evolutionarily conserved partner of the centralspindlin complex, a key regulator of cytokinesis. Nesd contains a pectin lyase-like domain found in proteins that bind to polysaccharides, and we present evidence that it has high affinity for ß-galactosides in vitro. Moreover, nesd is an essential gene in Drosophila melanogaster, in which it is required for completion of cytokinesis during male meiosis and possibly in female germline cells. Our findings indicate that Nesd is a novel carbohydrate-binding protein that functions together with centralspindlin in late cytokinesis, thus highlighting the importance of glycosylation in this process.
Assuntos
Citocinese/fisiologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/fisiologia , Meiose/fisiologia , Proteínas Associadas aos Microtúbulos/genética , Espermatócitos/citologia , Fuso Acromático/metabolismo , Actinas/metabolismo , Sequência de Aminoácidos , Animais , Linhagem Celular , Proteínas Contráteis/metabolismo , Proteínas de Drosophila/genética , Feminino , Proteínas Ativadoras de GTPase/genética , Proteínas Ativadoras de GTPase/metabolismo , Galactosídeos/metabolismo , Células Germinativas/citologia , Células Germinativas/metabolismo , Humanos , Masculino , Proteínas Associadas aos Microtúbulos/metabolismo , Dados de Sequência Molecular , Complexos Multiproteicos/metabolismo , Miosina Tipo II/genética , Miosina Tipo II/metabolismo , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Filogenia , Polissacarídeos/metabolismo , Ligação Proteica/fisiologia , Domínios e Motivos de Interação entre Proteínas/fisiologia , Espermatócitos/metabolismo , Telófase/fisiologiaRESUMO
BACKGROUND: Small untranslated RNAs (sRNAs) seem to be far more abundant than previously believed. The number of sRNAs confirmed in E. coli through various approaches is above 70, with several hundred more sRNA candidate genes under biological validation. Although the total number of sRNAs in any one species is still unclear, their importance in cellular processes has been established. However, unlike protein genes, no simple feature enables the prediction of the location of the corresponding sequences in genomes. Several approaches, of variable usefulness, to identify genomic sequences encoding sRNA have been described in recent years. RESULTS: We used a combination of in silico comparative genomics and microarray-based transcriptional profiling. This approach to screening identified ~60 intergenic regions conserved between Sinorhizobium meliloti and related members of the alpha-proteobacteria sub-group 2. Of these, 14 appear to correspond to novel non-coding sRNAs and three are putative peptide-coding or 5' UTR RNAs (ORF smaller than 100 aa). The expression of each of these new small RNA genes was confirmed by Northern blot hybridization. CONCLUSION: Small non coding RNA (sra) genes can be found in the intergenic regions of alpha-proteobacteria genomes. Some of these sra genes are only present in S. meliloti, sometimes in genomic islands; homologues of others are present in related genomes including those of the pathogens Brucella and Agrobacterium.
Assuntos
Genômica/métodos , RNA Nuclear/genética , RNA não Traduzido/genética , Sinorhizobium meliloti/genética , Alphaproteobacteria/classificação , Alphaproteobacteria/genética , Sequência de Bases , Northern Blotting , Biologia Computacional/métodos , Perfilação da Expressão Gênica , Genoma Bacteriano , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Análise de Sequência com Séries de Oligonucleotídeos , RNA Bacteriano/química , RNA Bacteriano/genética , RNA Longo não Codificante , RNA não Traduzido/química , Homologia de Sequência do Ácido Nucleico , Transcrição GênicaRESUMO
Toxin/antitoxin (TA) systems, viewed as essential regulators of growth arrest and programmed cell death, are widespread among prokaryotes, but remain sparsely annotated. We present RASTA-Bacteria, an automated method allowing quick and reliable identification of TA loci in sequenced prokaryotic genomes, whether they are annotated open reading frames or not. The tool successfully confirmed all reported TA systems, and spotted new putative loci upon screening of sequenced genomes. RASTA-Bacteria is publicly available at http://genoweb.univ-rennes1.fr/duals/RASTA-Bacteria.