RESUMEN
Natural resistance to lincosamides and streptogramins A (LSA), which is a species characteristic of Bacillus subtilis and Enterococcus faecalis, has never been documented in the Staphylococcus genus. We investigate here the molecular basis of the LSA phenotype exhibited by seven reference strains of Staphylococcus sciuri, including the type strains of the three described subspecies. By whole-genome sequencing of strain ATCC 29059, we identified a candidate gene that encodes an ATP-binding cassette protein similar to the Lsa and VmlR resistance determinants. Isolation and reverse transcription-quantitative PCR (qRT-PCR) expression studies confirmed that Sal(A) can confer a moderate resistance to lincosamides (8 times the MIC of lincomycin) and a high-level resistance to streptogramins A (64 times the MIC of pristinamycin II). The chromosomal location of sal(A) between two housekeeping genes of the staphylococcal core genome supports the gene's ancient origins and thus innate resistance to these antimicrobials within S. sciuri subspecies.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/genética , Farmacorresistencia Bacteriana Múltiple , Lincosamidas/farmacología , Infecciones Estafilocócicas/microbiología , Staphylococcus/genética , Estreptogramina A/farmacología , Secuencia de Aminoácidos , Proteínas Bacterianas/metabolismo , Mapeo Cromosómico , ADN Bacteriano/química , ADN Bacteriano/genética , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , Fenotipo , Filogenia , Alineación de Secuencia , Análisis de Secuencia de ADN , Staphylococcus/efectos de los fármacosRESUMEN
There exist numerous genes disseminated by mobile elements that can confer cross-resistance to lincosamides and streptogramin A compounds in staphylococci. This study investigated the nature and means of dissemination of genes responsible for LSA resistance among 24 French clinical isolates screened for reduced susceptibility to lincomycin. The vga(A)v gene was found to be the most prevalent determinant of LSA resistance, while Tn5406 appeared to be its exclusive gene support.
RESUMEN
Staphylococcus sciuri is considered to be one of the most ancestral species in the natural history of the Staphylococcus genus that consists of 48 validly described species. It belongs to the basal group of oxidase-positive and novobiocin-resistant staphylococci that diverged from macrococci approximately 250 million years ago. Contrary to other groups, the S. sciuri species group has not developed host-specific colonization strategies. Genome analysis of S. sciuri ATCC 29059 provides here the first genetic basis for atypical traits that would support the switch between the free-living style and the infective state in animals and humans. From among the most remarkable features, it was noticed in this extensive study that there were a number of phosphoenolpyruvate:carbohydrate phosphotransferase systems (PTS), almost twice as many as any other staphylococci, and the co-occurrence of mevalonate and non-mevalonate pathways for isoprenoid synthesis. The sequenced strain was devoid of the main virulence factors present in Staphylococcus aureus, although it exhibited numerous heme and iron acquisition systems, as well as crt and aldH genes necessary for gold pigment synthesis. The sensing and signaling networks, exemplified by a large and typical repertoire of two-component regulatory systems and a complete panel of master regulators, such as agr, rex, mgrA, rot, sarA and sarR genes, depict the background in which S. aureus virulence genes were later acquired. An additional sigma factor, a distinct set of electron transducer elements and many gene operons similar to those found in Bacillus spp. would constitute the most visible remnant links with Bacillaceae organisms.
Asunto(s)
Genoma Bacteriano/genética , Oxidorreductasas/metabolismo , Staphylococcus , Transportadoras de Casetes de Unión a ATP/genética , Secuencia de Bases , Farmacorresistencia Bacteriana/genética , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Ácido Mevalónico/metabolismo , Novobiocina/farmacología , Fenotipo , Sistema de Fosfotransferasa de Azúcar del Fosfoenolpiruvato/genética , Análisis de Secuencia de ADN , Factor sigma/genética , Staphylococcus/clasificación , Staphylococcus/efectos de los fármacos , Staphylococcus/genética , Staphylococcus/metabolismo , Terpenos/metabolismoRESUMEN
We present here a Sleeping Beauty-based transposition system that offers a simple and efficient way to investigate the regulatory architecture of mammalian chromosomes in vivo. With this system, we generated several hundred mice and embryos, each with a regulatory sensor inserted at a random genomic position. This large sampling of the genome revealed the widespread presence of long-range regulatory activities along chromosomes, forming overlapping blocks with distinct tissue-specific expression potentials. The presence of tissue-restricted regulatory activities around genes with widespread expression patterns challenges the gene-centric view of genome regulation and suggests that most genes are modulated in a tissue-specific manner. The local hopping property of Sleeping Beauty provides a dynamic approach to map these regulatory domains at high resolution and, combined with Cre-mediated recombination, allows for the determination of their functions by engineering mice with specific chromosomal rearrangements.