RESUMO
The complete genome sequence of Treponema pallidum was determined and shown to be 1,138,006 base pairs containing 1041 predicted coding sequences (open reading frames). Systems for DNA replication, transcription, translation, and repair are intact, but catabolic and biosynthetic activities are minimized. The number of identifiable transporters is small, and no phosphoenolpyruvate:phosphotransferase carbohydrate transporters were found. Potential virulence factors include a family of 12 potential membrane proteins and several putative hemolysins. Comparison of the T. pallidum genome sequence with that of another pathogenic spirochete, Borrelia burgdorferi, the agent of Lyme disease, identified unique and common genes and substantiates the considerable diversity observed among pathogenic spirochetes.
Assuntos
Genoma Bacteriano , Análise de Sequência de DNA , Treponema pallidum/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Bases , Grupo Borrelia Burgdorferi/genética , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Reparo do DNA/genética , Replicação do DNA/genética , Enzimas de Restrição do DNA/genética , Metabolismo Energético/genética , Genes Bacterianos , Genes Reguladores , Resposta ao Choque Térmico/genética , Lipoproteínas/genética , Proteínas de Membrana/genética , Dados de Sequência Molecular , Movimento , Fases de Leitura Aberta , Consumo de Oxigênio/genética , Biossíntese de Proteínas , Recombinação Genética , Origem de Replicação , Transcrição Gênica , Treponema pallidum/metabolismo , Treponema pallidum/patogenicidadeRESUMO
The 2,272,351-base pair genome of Neisseria meningitidis strain MC58 (serogroup B), a causative agent of meningitis and septicemia, contains 2158 predicted coding regions, 1158 (53.7%) of which were assigned a biological role. Three major islands of horizontal DNA transfer were identified; two of these contain genes encoding proteins involved in pathogenicity, and the third island contains coding sequences only for hypothetical proteins. Insights into the commensal and virulence behavior of N. meningitidis can be gleaned from the genome, in which sequences for structural proteins of the pilus are clustered and several coding regions unique to serogroup B capsular polysaccharide synthesis can be identified. Finally, N. meningitidis contains more genes that undergo phase variation than any pathogen studied to date, a mechanism that controls their expression and contributes to the evasion of the host immune system.
Assuntos
Genoma Bacteriano , Neisseria meningitidis/genética , Neisseria meningitidis/patogenicidade , Análise de Sequência de DNA , Variação Antigênica , Antígenos de Bactérias/imunologia , Bacteriemia/microbiologia , Cápsulas Bacterianas/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Elementos de DNA Transponíveis , Evolução Molecular , Fímbrias Bacterianas/genética , Humanos , Meningite Meningocócica/microbiologia , Infecções Meningocócicas/microbiologia , Dados de Sequência Molecular , Mutação , Neisseria meningitidis/classificação , Neisseria meningitidis/fisiologia , Fases de Leitura Aberta , Óperon , Filogenia , Recombinação Genética , Sorotipagem , Transformação Bacteriana , Virulência/genéticaRESUMO
The genome of the bacterium Borrelia burgdorferi B31, the aetiologic agent of Lyme disease, contains a linear chromosome of 910,725 base pairs and at least 17 linear and circular plasmids with a combined size of more than 533,000 base pairs. The chromosome contains 853 genes encoding a basic set of proteins for DNA replication, transcription, translation, solute transport and energy metabolism, but, like Mycoplasma genitalium, it contains no genes for cellular biosynthetic reactions. Because B. burgdorferi and M. genitalium are distantly related eubacteria, we suggest that their limited metabolic capacities reflect convergent evolution by gene loss from more metabolically competent progenitors. Of 430 genes on 11 plasmids, most have no known biological function; 39% of plasmid genes are paralogues that form 47 gene families. The biological significance of the multiple plasmid-encoded genes is not clear, although they may be involved in antigenic variation or immune evasion.
Assuntos
Grupo Borrelia Burgdorferi/genética , Genoma Bacteriano , Transporte Biológico , Quimiotaxia , Cromossomos Bacterianos , Reparo do DNA , DNA Bacteriano/biossíntese , DNA Bacteriano/genética , Metabolismo Energético , Regulação Bacteriana da Expressão Gênica , Doença de Lyme/microbiologia , Proteínas de Membrana/genética , Dados de Sequência Molecular , Plasmídeos , Biossíntese de Proteínas , Recombinação Genética , Origem de Replicação , Telômero , Transcrição GênicaRESUMO
The 1,860,725-base-pair genome of Thermotoga maritima MSB8 contains 1,877 predicted coding regions, 1,014 (54%) of which have functional assignments and 863 (46%) of which are of unknown function. Genome analysis reveals numerous pathways involved in degradation of sugars and plant polysaccharides, and 108 genes that have orthologues only in the genomes of other thermophilic Eubacteria and Archaea. Of the Eubacteria sequenced to date, T. maritima has the highest percentage (24%) of genes that are most similar to archaeal genes. Eighty-one archaeal-like genes are clustered in 15 regions of the T. maritima genome that range in size from 4 to 20 kilobases. Conservation of gene order between T. maritima and Archaea in many of the clustered regions suggests that lateral gene transfer may have occurred between thermophilic Eubacteria and Archaea.
Assuntos
Archaea/genética , Genoma Bacteriano , Recombinação Genética , Thermotoga maritima/genética , Proteínas de Bactérias/metabolismo , DNA Bacteriano , Genes Arqueais , Dados de Sequência Molecular , Família Multigênica , Fases de Leitura Aberta , Filogenia , Biossíntese de Proteínas , Análise de Sequência de DNA , Thermotoga maritima/classificação , Thermotoga maritima/fisiologia , Transcrição Gênica , Transformação BacterianaRESUMO
Helicobacter pylori, strain 26695, has a circular genome of 1,667,867 base pairs and 1,590 predicted coding sequences. Sequence analysis indicates that H. pylori has well-developed systems for motility, for scavenging iron, and for DNA restriction and modification. Many putative adhesins, lipoproteins and other outer membrane proteins were identified, underscoring the potential complexity of host-pathogen interaction. Based on the large number of sequence-related genes encoding outer membrane proteins and the presence of homopolymeric tracts and dinucleotide repeats in coding sequences, H. pylori, like several other mucosal pathogens, probably uses recombination and slipped-strand mispairing within repeats as mechanisms for antigenic variation and adaptive evolution. Consistent with its restricted niche, H. pylori has a few regulatory networks, and a limited metabolic repertoire and biosynthetic capacity. Its survival in acid conditions depends, in part, on its ability to establish a positive inside-membrane potential in low pH.
Assuntos
Genoma Bacteriano , Helicobacter pylori/genética , Variação Antigênica , Aderência Bacteriana , Proteínas de Bactérias/metabolismo , Sequência de Bases , Evolução Biológica , Divisão Celular , Reparo do DNA , DNA Bacteriano/genética , Regulação Bacteriana da Expressão Gênica , Helicobacter pylori/metabolismo , Helicobacter pylori/patogenicidade , Concentração de Íons de Hidrogênio , Dados de Sequência Molecular , Biossíntese de Proteínas , Recombinação Genética , Transcrição Gênica , VirulênciaRESUMO
Archaeoglobus fulgidus is the first sulphur-metabolizing organism to have its genome sequence determined. Its genome of 2,178,400 base pairs contains 2,436 open reading frames (ORFs). The information processing systems and the biosynthetic pathways for essential components (nucleotides, amino acids and cofactors) have extensive correlation with their counterparts in the archaeon Methanococcus jannaschii. The genomes of these two Archaea indicate dramatic differences in the way these organisms sense their environment, perform regulatory and transport functions, and gain energy. In contrast to M. jannaschii, A. fulgidus has fewer restriction-modification systems, and none of its genes appears to contain inteins. A quarter (651 ORFs) of the A. fulgidus genome encodes functionally uncharacterized yet conserved proteins, two-thirds of which are shared with M. jannaschii (428 ORFs). Another quarter of the genome encodes new proteins indicating substantial archaeal gene diversity.