Extensive DNA Inversions in the
            <i>B. fragilis</i>
            Genome Control Variable Gene Expression

Cerdeño-Tárraga, Ana; Patrick, Sheila; Crossman, Lisa; Blakely, Garry W.; Abratt, Val; Lennard, Nicola; Poxton, Ian R.; Duerden, B. I.; Harris, Barbara; Quail, Mike; Barron, Andrew; Clark, Louise; Corton, Craig; Doggett, Jon; Holden, Matthew T. G.; Larke, Natasha; Line, Alexandra; Lord, Angela; Norbertczak, Halina; Ormond, Doug; Price, Claire; Rabbinowitsch, Ester; Woodward, John R.; Barrell, Bart; Parkhill, Julian

doi:10.1126/science.1107008

Cited by 281 publications

(209 citation statements)

References 22 publications

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“…There were genes for Hly type I secretion systems, which are similar to the hemolysin type I secretion system HlyDb from E. coli (288), or the type II general secretion pathway (54). The large quantity of enzyme-containing outer membrane vesicles produced by B. fragilis (185) suggests that this may be an important export pathway (54). The Bacteroides genome also contains large numbers of gene homologs of a variety of efflux pumps systems whose export functions have not yet been defined.…”

Section: Cell Surface Structuresmentioning

confidence: 99%

“…The genomic studies of B. fragilis did not show evidence of type III, IV, autotransporter, or two-partner secretion systems. There were genes for Hly type I secretion systems, which are similar to the hemolysin type I secretion system HlyDb from E. coli (288), or the type II general secretion pathway (54). The large quantity of enzyme-containing outer membrane vesicles produced by B. fragilis (185) suggests that this may be an important export pathway (54).…”

Section: Cell Surface Structuresmentioning

confidence: 99%

“…The completion of the sequencing projects for B. thetaiotaomicron in 2003 (306) and B. fragilis in 2004 to 2005 (54,138) and subsequent proteomic analyses have vastly added to our understanding of the manner in which these organisms adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense the nutrient available and tailor nutrient-metabolizing systems accordingly, (ii) multiple pump systems to rid the bacteria of toxic substances, and (iii) the ability to control the environment by interacting with the host immune system so that it controls other (competing) pathogens.…”

Section: Introductionmentioning

confidence: 99%

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Bacteroides: the Good, the Bad, and the Nitty-Gritty

2007

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SUMMARY Summary: Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).

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Section: Cell Surface Structuresmentioning

confidence: 99%

Section: Cell Surface Structuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bacteroides: the Good, the Bad, and the Nitty-Gritty

2007

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“…Pathogenic bacteria use the phase variability of gene expression to evade the host immune system. Based on sequence analysis and biochemical evidence, many type I and III enzymes of Bacteroides fragilis as well as Haemophilus, Helicobacter, Mycoplasma, and Neisseria species were found to be potentially phase variable (176)(177)(178)(179)(180)(181). The biological significance of R-M systems that exhibit phase variability is not completely understood.…”

Section: Functions Of Phase-variable R-m Systemsmentioning

confidence: 99%

“…(iii) Whole-genome sequencing of B. fragilis revealed that many R-M systems of bacteria undergo inversions (176). It has been proposed that phase variation in these bacteria increases the diversity of R-M systems, generating up to eight different recognition subunits (176 (180,181).…”

Section: Functions Of Phase-variable R-m Systemsmentioning

confidence: 99%

Diverse Functions of Restriction-Modification Systems in Addition to Cellular Defense

Vasu

Nagaraja

2013

Microbiol Mol Biol Rev

521

462

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SUMMARY Restriction-modification (R-M) systems are ubiquitous and are often considered primitive immune systems in bacteria. Their diversity and prevalence across the prokaryotic kingdom are an indication of their success as a defense mechanism against invading genomes. However, their cellular defense function does not adequately explain the basis for their immaculate specificity in sequence recognition and nonuniform distribution, ranging from none to too many, in diverse species. The present review deals with new developments which provide insights into the roles of these enzymes in other aspects of cellular function. In this review, emphasis is placed on novel hypotheses and various findings that have not yet been dealt with in a critical review. Emerging studies indicate their role in various cellular processes other than host defense, virulence, and even controlling the rate of evolution of the organism. We also discuss how R-M systems could have successfully evolved and be involved in additional cellular portfolios, thereby increasing the relative fitness of their hosts in the population.

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TheNrfHCytochromecQuinol Dehydrogenase

Rodrigues¹,

Pereira²,

Archer³

2004

Handbook of Metalloproteins

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RESEÑAS 249 Mariano de la Campa ("El Diálogo de las lenguas bajo la erudición del siglo xix", pp. 35-57) completa este panorama al trazar los hitos prin-cipales de la obra a lo largo del siglo xix, donde desfilan los nombres de Clemencín, Fernández de Moratín, pero muy especialmente Bar-tolomé José Gallardo, a quien debemos muchos avances respecto a las distintas noticias sobre los manuscritos coetáneos. Francisco Javier Satorre Grau ("El Diálogo de la lengua de Juan de Valdés y la gramática de su época", pp. 59-81) sitúa, con economía y mucha claridad, las piezas clave del diálogo valdesiano desde una perspectiva coetánea: no es una gramática y más bien se desprecian las reglas en aras de los usos y costumbres; su proyección didáctica es amplia, pues los tres interlocutores ofrecen diferentes visiones de mundo (Pacheco, el hispanohablante no ilustrado; Corioliano, el italiano que apenas aprende la lengua; Marcio, el italiano culto que conoce la lengua), por lo que las preguntas pueden ir desde lo más elemental hasta lo más complejo; su perfil anecdótico convierte el Diálogo en una obra con la que Valdés respondía a las dudas de su círculo de amistades y, en ese sentido, es como debemos leerlo hoy. El último estudio, a cargo de María Teresa Echenique Elizondo ("En torno al Dialogo de la lengua y la presente edición", pp. 83-92), ofrece un apretado estado de la cuestión que muestra la vigencia del diálogo de Valdés y que sirve de preludio para explicar la situación en la que se concibe esta edición. La edición del Diálogo de la lengua de Rafael Lapesa representa, como trabajo colectivo y homenaje, una deuda de amor y de respeto académico saldada por su discípulos; pero más allá de la anécdota que le da origen, sus aportes son palpables: un nuevo texto críti-co que recupera las lecciones originales del manuscrito de Madrid a través de los ojos de uno de nuestros principales historiadores de la lengua, el rescate de sus notas y el agregado de estudios originales que vuelven sobre los grandes temas del Diálogo. Valdés, sin duda, fue un enamorado de la lengua española; era justo que Rafael La-pesa, de quien no podemos decir menos, cumpliera su promesa de entregarnos una edición que superara a la del joven académico que fue en 1940, incluso después de su partida.

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Extensive DNA Inversions in the B. fragilis Genome Control Variable Gene Expression

Cited by 281 publications

References 22 publications

Bacteroides: the Good, the Bad, and the Nitty-Gritty

Bacteroides: the Good, the Bad, and the Nitty-Gritty

Diverse Functions of Restriction-Modification Systems in Addition to Cellular Defense

TheNrfHCytochromecQuinol Dehydrogenase

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