RESUMEN
Sequencing and comparative genome analysis of four strains of Campylobacter including C. lari RM2100, C. upsaliensis RM3195, and C. coli RM2228 has revealed major structural differences that are associated with the insertion of phage- and plasmid-like genomic islands, as well as major variations in the lipooligosaccharide complex. Poly G tracts are longer, are greater in number, and show greater variability in C. upsaliensis than in the other species. Many genes involved in host colonization, including racR/S, cadF, cdt, ciaB, and flagellin genes, are conserved across the species, but variations that appear to be species specific are evident for a lipooligosaccharide locus, a capsular (extracellular) polysaccharide locus, and a novel Campylobacter putative licABCD virulence locus. The strains also vary in their metabolic profiles, as well as their resistance profiles to a range of antibiotics. It is evident that the newly identified hypothetical and conserved hypothetical proteins, as well as uncharacterized two-component regulatory systems and membrane proteins, may hold additional significant information on the major differences in virulence among the species, as well as the specificity of the strains for particular hosts.
Asunto(s)
Campylobacter/genética , Campylobacter/patogenicidad , Genoma Bacteriano , Virulencia/genética , Animales , Proteínas Bacterianas/genética , Enfermedades de las Aves/microbiología , Aves , Campylobacter/clasificación , Bovinos , Enfermedades de los Bovinos/microbiología , Funciones de Verosimilitud , Datos de Secuencia Molecular , Filogenia , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Porcinos , Enfermedades de los Porcinos/microbiologíaRESUMEN
The genetic relatedness of the Bacillus anthracis typing phages Gamma and Cherry was determined by nucleotide sequencing and comparative analysis. The genomes of these two phages were identical except at three variable loci, which showed heterogeneity within individual lysates and among Cherry, Wbeta, Fah, and four Gamma bacteriophage sequences.
Asunto(s)
Fagos de Bacillus/genética , Genoma Viral , Fagos de Bacillus/clasificación , Bacillus anthracis/virología , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Especificidad de la EspecieRESUMEN
Cryptococcus neoformans is a basidiomycetous yeast ubiquitous in the environment, a model for fungal pathogenesis, and an opportunistic human pathogen of global importance. We have sequenced its approximately 20-megabase genome, which contains approximately 6500 intron-rich gene structures and encodes a transcriptome abundant in alternatively spliced and antisense messages. The genome is rich in transposons, many of which cluster at candidate centromeric regions. The presence of these transposons may drive karyotype instability and phenotypic variation. C. neoformans encodes unique genes that may contribute to its unusual virulence properties, and comparison of two phenotypically distinct strains reveals variation in gene content in addition to sequence polymorphisms between the genomes.
Asunto(s)
Cryptococcus neoformans/genética , Genoma Fúngico , Empalme Alternativo , Pared Celular/metabolismo , Cromosomas Fúngicos/genética , Biología Computacional , Cryptococcus neoformans/patogenicidad , Cryptococcus neoformans/fisiología , Elementos Transponibles de ADN , Proteínas Fúngicas/metabolismo , Biblioteca de Genes , Genes Fúngicos , Humanos , Intrones , Datos de Secuencia Molecular , Fenotipo , Polimorfismo Genético , Polimorfismo de Nucleótido Simple , Polisacáridos/metabolismo , ARN sin Sentido , Análisis de Secuencia de ADN , Transcripción Genética , Virulencia , Factores de Virulencia/metabolismoRESUMEN
We present the complete 2,843,201-bp genome sequence of Treponema denticola (ATCC 35405) an oral spirochete associated with periodontal disease. Analysis of the T. denticola genome reveals factors mediating coaggregation, cell signaling, stress protection, and other competitive and cooperative measures, consistent with its pathogenic nature and lifestyle within the mixed-species environment of subgingival dental plaque. Comparisons with previously sequenced spirochete genomes revealed specific factors contributing to differences and similarities in spirochete physiology as well as pathogenic potential. The T. denticola genome is considerably larger in size than the genome of the related syphilis-causing spirochete Treponema pallidum. The differences in gene content appear to be attributable to a combination of three phenomena: genome reduction, lineage-specific expansions, and horizontal gene transfer. Genes lost due to reductive evolution appear to be largely involved in metabolism and transport, whereas some of the genes that have arisen due to lineage-specific expansions are implicated in various pathogenic interactions, and genes acquired via horizontal gene transfer are largely phage-related or of unknown function.