RESUMO
The complete sequence of pMRC01, a large conjugative plasmid from Lactococcus lactis ssp. lactis DPC3147, has been determined. Using a shotgun sequencing approach, the 60,232 bp plasmid sequence was obtained by the assembly of 1056 underlying sequences (sevenfold average redundancy). Sixty-four open reading frames (ORFs) were identified. Analysis of the gene organization of pMRC01 suggests that the plasmid can be divided into three functional domains, with each approximately 20 kb region separated by insertion sequence (IS) elements. The three regions are (i) the conjugative transfer region, including a 16-gene Tra (transfer) operon; (ii) the bacteriocin production region, including an operon responsible for the synthesis of the novel bacteriocin lacticin 3147; and (iii) the phage resistance and plasmid replication region of the plasmid. The complete sequence of pMRC01 provides important information about these industrially relevant phenotypes and gives insight into the structure, function and evolution of large gram-positive conjugative plasmids in general. The completely sequenced pMRC01 plasmid should also provide a useful framework for the design of novel plasmids to be incorporated into starter strain improvement programmes for the dairy industry.
Assuntos
Bacteriocinas/biossíntese , Bacteriocinas/genética , Lactococcus lactis/genética , Lactococcus lactis/metabolismo , Plasmídeos/genética , Bacteriófagos/patogenicidade , Sequência de Bases , Mapeamento Cromossômico , Conjugação Genética , Elementos de DNA Transponíveis/genética , DNA Bacteriano/genética , Genes Bacterianos , Lactococcus lactis/virologia , Dados de Sequência Molecular , Fases de Leitura Aberta , Fenótipo , Homologia de Sequência do Ácido NucleicoRESUMO
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.
Assuntos
Archaeoglobus fulgidus/genética , Genes Arqueais , Genoma , Archaeoglobus fulgidus/metabolismo , Archaeoglobus fulgidus/fisiologia , Sequência de Bases , Divisão Celular , DNA Bacteriano/genética , Metabolismo Energético , Regulação Bacteriana da Expressão Gênica , Dados de Sequência Molecular , Biossíntese de Proteínas , Transcrição GênicaRESUMO
The complete nucleotide sequence (580,070 base pairs) of the Mycoplasma genitalium genome, the smallest known genome of any free-living organism, has been determined by whole-genome random sequencing and assembly. A total of only 470 predicted coding regions were identified that include genes required for DNA replication, transcription and translation, DNA repair, cellular transport, and energy metabolism. Comparison of this genome to that of Haemophilus influenzae suggests that differences in genome content are reflected as profound differences in physiology and metabolic capacity between these two organisms.