RESUMO
BACKGROUND: Listeria monocytogenes is a food-borne pathogen that causes infections with a high-mortality rate and has served as an invaluable model for intracellular parasitism. Here, we report complete genome sequences for two L. monocytogenes strains belonging to serotype 4a (L99) and 4b (CLIP80459), and transcriptomes of representative strains from lineages I, II, and III, thereby permitting in-depth comparison of genome- and transcriptome -based data from three lineages of L. monocytogenes. Lineage III, represented by the 4a L99 genome is known to contain strains less virulent for humans. RESULTS: The genome analysis of the weakly pathogenic L99 serotype 4a provides extensive evidence of virulence gene decay, including loss of several important surface proteins. The 4b CLIP80459 genome, unlike the previously sequenced 4b F2365 genome harbours an intact inlB invasion gene. These lineage I strains are characterized by the lack of prophage genes, as they share only a single prophage locus with other L. monocytogenes genomes 1/2a EGD-e and 4a L99. Comparative transcriptome analysis during intracellular growth uncovered adaptive expression level differences in lineages I, II and III of Listeria, notable amongst which was a strong intracellular induction of flagellar genes in strain 4a L99 compared to the other lineages. Furthermore, extensive differences between strains are manifest at levels of metabolic flux control and phosphorylated sugar uptake. Intriguingly, prophage gene expression was found to be a hallmark of intracellular gene expression. Deletion mutants in the single shared prophage locus of lineage II strain EGD-e 1/2a, the lma operon, revealed severe attenuation of virulence in a murine infection model. CONCLUSION: Comparative genomics and transcriptome analysis of L. monocytogenes strains from three lineages implicate prophage genes in intracellular adaptation and indicate that gene loss and decay may have led to the emergence of attenuated lineages.
Assuntos
Perfilação da Expressão Gênica/métodos , Genômica/métodos , Listeria monocytogenes/genética , Filogenia , Animais , Bacteriófagos/genética , Modelos Animais de Doenças , Flagelina/metabolismo , Duplicação Gênica/genética , Regulação Bacteriana da Expressão Gênica , Transferência Genética Horizontal/genética , Genes Virais/genética , Loci Gênicos/genética , Genoma Bacteriano , Humanos , Listeria monocytogenes/metabolismo , Listeria monocytogenes/patogenicidade , Listeria monocytogenes/virologia , Listeriose/microbiologia , Proteínas de Membrana/metabolismo , Camundongos , Dados de Sequência Molecular , Família Multigênica/genética , Mutação/genética , Motivos de Nucleotídeos/genética , Nucleotídeos/genética , Polimorfismo de Nucleotídeo Único/genética , Sequências Repetitivas de Ácido Nucleico/genética , Virulência/genéticaRESUMO
We report the complete and annotated genome sequence of the nonpathogenic Listeria seeligeri SLCC3954 serovar 1/2b type strain harboring the smallest completely sequenced genome of the genus Listeria.
Assuntos
DNA Bacteriano/química , DNA Bacteriano/genética , Genoma Bacteriano , Listeria/genética , Dados de Sequência Molecular , Análise de Sequência de DNARESUMO
This review provides an overview of recent progress in the exploration of genomic, transcriptomic, and proteomic data in Listeria spp. to understand genome evolution and diversity, as well as physiological aspects of metabolism utilized by the bacteria when growing in diverse and varied environments.
Assuntos
Listeria/genética , Proteômica , Virulência/genética , Cromossomos Bacterianos , Perfilação da Expressão Gênica/métodos , Listeria/classificação , Listeria/patogenicidade , Análise de Sequência com Séries de Oligonucleotídeos/métodos , FilogeniaRESUMO
We present the complete genome sequence of Listeria welshimeri, a nonpathogenic member of the genus Listeria. Listeria welshimeri harbors a circular chromosome of 2,814,130 bp with 2,780 open reading frames. Comparative genomic analysis of chromosomal regions between L. welshimeri, Listeria innocua, and Listeria monocytogenes shows strong overall conservation of synteny, with the exception of the translocation of an F(o)F(1) ATP synthase. The smaller size of the L. welshimeri genome is the result of deletions in all of the genes involved in virulence and of "fitness" genes required for intracellular survival, transcription factors, and LPXTG- and LRR-containing proteins as well as 55 genes involved in carbohydrate transport and metabolism. In total, 482 genes are absent from L. welshimeri relative to L. monocytogenes. Of these, 249 deletions are commonly absent in both L. welshimeri and L. innocua, suggesting similar genome evolutionary paths from an ancestor. We also identified 311 genes specific to L. welshimeri that are absent in the other two species, indicating gene expansion in L. welshimeri, including horizontal gene transfer. The species L. welshimeri appears to have been derived from early evolutionary events and an ancestor more compact than L. monocytogenes that led to the emergence of nonpathogenic Listeria spp.
Assuntos
DNA Bacteriano/genética , Evolução Molecular , Genoma Bacteriano , Listeria/genética , Análise de Sequência de DNA , Cromossomos Bacterianos/genética , DNA Bacteriano/química , Deleção de Genes , Ordem dos Genes , Transferência Genética Horizontal , Listeria monocytogenes/genética , ATPases Mitocondriais Próton-Translocadoras/genética , Dados de Sequência Molecular , Fases de Leitura Aberta , Filogenia , Sintenia , Translocação GenéticaRESUMO
The genus Listeria comprises a group of non-sporulating, Gram-positive, soil bacteria belonging to the low G+C group of microorganisms. The genus consists of only six species, L. monocytogenes, L. ivanovii, L. seeligeri, L. innocua, L. welshimeri, and L. grayi.L. monocytogenes and L. ivanovii are the only known pathogens of this group. Comparative whole-genome sequencing of representative strains comprising the entire genus is currently being performed and nearing completion. In the genus Listeria, genome reduction has led to the generation of non-pathogenic species from pathogenic progenitor strains. Indeed, many of the regions absent in the non-pathogenic species represent commonly deleted genes. Speciation and diversity of strains has been achieved by horizontal gene transfer of DNA encoding novel genes probably required for niche specific survival. The sequencing of several listerial genomes has also been accompanied by studies using global strategies involving whole-genome transcriptional profiling and proteomics to examine the adaptative changes of L. monocytogenes to growth in different environments and to catalogue the genes mediating these responses. We review this data and present information on the expression profile of L. monocytogenes EGD-e inside the vacuolar and the cytosolic environments of the host cell using whole-genome microarray analysis. Of the 484 genes regulated during intracellular growth 41 genes are species-specific, being absent from the genome of the non-pathogenic L. innocua CLIP 11262 strain. There were 25 genes that are strain-specific i.e. absent from the genome of the L. monocytogenes F2365 serotype 4b strain suggesting heterogeneity in the gene pool required for intracellular survival of L. monocytogenes in host cells.
