RESUMO
Myxobacteria are single-celled, but social, eubacterial predators. Upon starvation they build multicellular fruiting bodies using a developmental program that progressively changes the pattern of cell movement and the repertoire of genes expressed. Development terminates with spore differentiation and is coordinated by both diffusible and cell-bound signals. The growth and development of Myxococcus xanthus is regulated by the integration of multiple signals from outside the cells with physiological signals from within. A collection of M. xanthus cells behaves, in many respects, like a multicellular organism. For these reasons M. xanthus offers unparalleled access to a regulatory network that controls development and that organizes cell movement on surfaces. The genome of M. xanthus is large (9.14 Mb), considerably larger than the other sequenced delta-proteobacteria. We suggest that gene duplication and divergence were major contributors to genomic expansion from its progenitor. More than 1,500 duplications specific to the myxobacterial lineage were identified, representing >15% of the total genes. Genes were not duplicated at random; rather, genes for cell-cell signaling, small molecule sensing, and integrative transcription control were amplified selectively. Families of genes encoding the production of secondary metabolites are overrepresented in the genome but may have been received by horizontal gene transfer and are likely to be important for predation.
Assuntos
Evolução Molecular , Genoma Bacteriano , Myxococcus xanthus/genética , Deltaproteobacteria/genética , Deltaproteobacteria/fisiologia , Dados de Sequência Molecular , Família Multigênica , Myxococcus xanthus/crescimento & desenvolvimento , Myxococcus xanthus/fisiologia , RNA Ribossômico 16S/genética , Transdução de Sinais/genética , Transdução de Sinais/fisiologiaRESUMO
The complete genome sequence of Geobacter sulfurreducens, a delta-proteobacterium, reveals unsuspected capabilities, including evidence of aerobic metabolism, one-carbon and complex carbon metabolism, motility, and chemotactic behavior. These characteristics, coupled with the possession of many two-component sensors and many c-type cytochromes, reveal an ability to create alternative, redundant, electron transport networks and offer insights into the process of metal ion reduction in subsurface environments. As well as playing roles in the global cycling of metals and carbon, this organism clearly has the potential for use in bioremediation of radioactive metals and in the generation of electricity.
Assuntos
Genoma Bacteriano , Geobacter/genética , Geobacter/metabolismo , Metais/metabolismo , Acetatos/metabolismo , Acetilcoenzima A/metabolismo , Aerobiose , Anaerobiose , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Carbono/metabolismo , Quimiotaxia , Cromossomos Bacterianos/genética , Citocromos c/genética , Citocromos c/metabolismo , Transporte de Elétrons , Metabolismo Energético , Genes Bacterianos , Genes Reguladores , Geobacter/fisiologia , Hidrogênio/metabolismo , Movimento , Fases de Leitura Aberta , Oxirredução , FilogeniaRESUMO
The complete genome sequence of Enterococcus faecalis V583, a vancomycin-resistant clinical isolate, revealed that more than a quarter of the genome consists of probable mobile or foreign DNA. One of the predicted mobile elements is a previously unknown vanB vancomycin-resistance conjugative transposon. Three plasmids were identified, including two pheromone-sensing conjugative plasmids, one encoding a previously undescribed pheromone inhibitor. The apparent propensity for the incorporation of mobile elements probably contributed to the rapid acquisition and dissemination of drug resistance in the enterococci.
Assuntos
Evolução Biológica , Enterococcus faecalis/genética , Genoma Bacteriano , Sequências Repetitivas Dispersas , Análise de Sequência de DNA , Resistência a Vancomicina/genética , Adesinas Bacterianas/genética , Aderência Bacteriana , Proteínas de Bactérias/genética , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Cromossomos Bacterianos/genética , Conjugação Genética , Sequência Conservada , Elementos de DNA Transponíveis , Sistema Digestório/microbiologia , Farmacorresistência Bacteriana Múltipla , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/patogenicidade , Enterococcus faecalis/fisiologia , Transferência Genética Horizontal , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Lisogenia , Fases de Leitura Aberta , Estresse Oxidativo , Plasmídeos , Sintenia , Virulência/genética , Fatores de Virulência/genéticaRESUMO
Pseudomonas putida is a metabolically versatile saprophytic soil bacterium that has been certified as a biosafety host for the cloning of foreign genes. The bacterium also has considerable potential for biotechnological applications. Sequence analysis of the 6.18 Mb genome of strain KT2440 reveals diverse transport and metabolic systems. Although there is a high level of genome conservation with the pathogenic Pseudomonad Pseudomonas aeruginosa (85% of the predicted coding regions are shared), key virulence factors including exotoxin A and type III secretion systems are absent. Analysis of the genome gives insight into the non-pathogenic nature of P. putida and points to potential new applications in agriculture, biocatalysis, bioremediation and bioplastic production.