Étude de la variation de phase des fimbriae F1651, Pap et CS31A et de l'impact des régulateurs homologues de PapI

Les Escherichia coli pathogènes extra-intestinaux (ExPEC) sont responsables d’une grande variété de maladies. Plus particulièrement, certaines souches ExPEC, du sous-groupe d’E. coli uropathogènes, sont porteuses de fimbriae de type P. Cette famille d’adhésines est soumise à une régulation transcriptionnelle appelée variation de phase; un mécanisme du tout ou rien. Il s’agit d’une compétition entre deux protéines régulatrices : la Dam méthylase et la nucléoprotéine Lrp. Ce mécanisme est aussi soumis à l’influence des régulateurs locaux PapB et PapI, deux régulateurs essentiels. Afin d’étudier PapI et ses homologues ainsi que leur impact sur la variation de phase des fimbriae F1651, Pap et CS31A. Grâce à une fusion chromosomique entre la région régulatrice de clp et les gènes lacZYA, nous avons étudié l’effet, en trans, de PapI et FooI qui ont pu restaurer la variation de phase avec une forte tendance pour la phase OFF. Pour étudier l’action de ces protéines sur foo et pap, nous avons utilisé un système utilisant gfp comme gène rapporteur de l’activité des promoteurs des opérons pap et foo. Cela a permis d’observer la variation de phase au niveau cellulaire par cytométrie en flux et en temps réel par microscopie à fluorescence. Ces expériences ont confirmé que la population de cellules F1651 positives a un phénotype d’expression de F1651 partielle alors que les cellules Pap sont en majorité en phase OFF. PapI et FooI n’ont pas la même influence sur la variation de phase, puisque FooI favorise une plus grande fréquence de variation de phase.

I papi ed i vespri siciliani. Con documenti inediti.

Defense of the papacy in reply to attacks from the Italian Liberal party on the occasion of the 6th centenary celebration of the Sicilian vespers.

Annali di Roma, dalla sua fondazione sino a' di' nostri : opera corredata di serie cronologica dei re, dei consoli ed altri capi della repubblica, degl' imperatori, dei papi, dei senatori dell'ultimo evo e de' conservatori.

Apparently incomplete. Vol. 8 ends with the year 337 A.D.

Memorie presentate da piu' cardinali, arcivescovi e vescovi a sua altezza reale il duca d'Orleans reggente di Francia per impegnarlo a punire, e frenare gli attentati de' Quesnellisti dalla lingua francese nella italiana tradotte ed illustrate con prefazione, ragguaglio della storia del libro delle Riflessioni morali di Quesnello, e note interessanti, contro il Testimonio, e trionfo della dottrina di Pistoja e il discorso della monarchia universale de Papi stampato senza data di luogo nel MDLXXXIX.

Ref. en ICCU.

I papi e le università /

"Ragionamento letto nella romana Accademia degli Arcadi il 16 giugno 1865."

Storia dei papi da san Pietro a Pio IX.

Mode of access: Internet.

Gli Slavi ed i papi, pel Giovanni Marković.

Bibliographical footnotes.

Braque, the papi

Mode of access: Internet.

Diplomatica pontificia, ossieno osservazioni paleografiche ed erudite sulle bolle de' papi.

Diss.--Pontificia accademia romana di archeologia.

Diplomatica pontificia, ossieno Osservazioni paleografiche ed erudite sulle bolle dei papi,

Signed, "A. Theiner."

Tavole cronologiche de'consoli ordinarj, papi, imperadori, re de' Romani, re d'Italia, prefetti di Roma, dogi di Venezia, e di Genova, de' quali si fa menzione negl' Annali d'Italia dal principio dell' era volgare sino all' anno MDCCL /

Includes index.

De los niños, cartas con corazón y letras grandes, el último mensaje dale el piano a francés, papi, Jaime de rabia quebró el "bidrio" : a veces llegan cartas 7

Fondo Margaritainés Restrepo

Regulatory interplay between pap operons in uropathogenic Escherichia coli

Pathogenic bacteria have a large repertoire of surface organelles involved in adherence, motility and protein export, but how individual bacteria co-ordinate surface organelle expression to prevent interference and excessive immune stimulation is unclear. Phase variation is a mechanism by which expression of surface factors is limited to a fraction of the bacterial population; however, the presence of multiple homologous surface structures controlled by related mechanisms and regulators antagonizes the independent expression achieved by phase variation. To investigate whether other mechanisms have evolved to sort out the bacterial cell surface, we examined regulatory cross-talk between multiple phase-variable pyelonephritis-associated pili (pap) operons in Escherichia coli isolates associated with urinary tract infections. Allelic variation identified in the regulatory regions and regulators acts synergistically to limit coexpression of homologous fimbrial operons. In particular, there is evidence that papI is under positive selection and PapI variants displayed differences in their capacity to activate related pap operons. Alleles of the high-affinity binding site for PapB were shown to contain a variable number of (T/A)3 repeats occurring every 9 bp that altered the sensitivity of pap operon activation. Taken together with other examples of surface organelle cross-talk, we illustrate how this regulation could promote sequential expression.

Regulation of P-fimbrial phase variation frequencies in Escherichia coli CFT073

Adherence of uropathogenic Escherichia coli to host tissue is required for infection and is mediated by fimbriae, such as pyelonephritis-associated pili (Pap). Expression of P fimbriae is regulated by phase variation, and to date, phase transition frequencies have been measured only for pap regulatory region constructs integrated into the E. coli K-12 chromosome. The aim of this work was to measure P phase transition frequencies in clinical isolates for the first time, including frequencies for the sequenced strain E. coli CFT073. P fimbriation and associated phase transition frequencies were measured for two E. coli clinical isolates and compared with levels for homologous pap constructs in E. coli K-12. Fimbriation and off-to-on transition frequencies were always higher in the clinical isolate. It was concluded that the regulatory inputs controlling papI expression are likely to be different in E. coli CFT073 and E. coli K-12 as (i) phase variation could be stimulated in E. coli K-12 by induction of papI and (ii) the level of expression of a papI::gfp+ fusion was higher in E. coli CFT073 than in E. coli K-12. Furthermore, phase transition frequencies for the two E. coli CFT073 pap clusters were shown to be different depending on the culture conditions, indicating that there is a hierarchy of expression depending on signal inputs.