GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • 1995-1999  (3)
Publikationsart
Verlag/Herausgeber
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 33 (1999), S. 0 
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: A series of plasmids carrying an IRL-kan-IRR transposable cassette, in which IRL and IRR are the left- and right-terminal sequences of IS91, have been constructed. These cassettes could be complemented for transposition with similar efficiency when IS91 transposase was provided either in cis or in trans. A total of 87% of IS91 transposition products were simple insertions of the element, while the remaining 13% were plasmid fusions and co-integrates. When transposase expression was induced from an upstream lac promoter, transposition frequency increased approximately 100-fold. An open reading frame (ORF) present upstream of the transposase gene, ORF121, could be involved in target selection, as mutations affecting this ORF were altered in their insertion specificity. Intramolecular rearrangements were analysed by looking at transposition events disrupting a chloramphenicol resistance gene (cat ) located outside the transposable cassette. Plasmid instability resulting from insertion of an extra copy of IRL-kan-IRR within the cat gene was observed; transposition products contained a second copy of the cassette inserted either as a direct or as an inverted repeat. No deletion or inversion of the intervening DNA was observed. These results could be explained as a consequence of intramolecular transposition of IS91 according to a model of rolling-circle transposition.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    Oxford UK : Blackwell Science Ltd
    Molecular microbiology 24 (1997), S. 0 
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: The conjugative transfer region of the IncX plasmid R6K (TRAX) was analysed by transposon mutagenesis and DNA sequencing. Tn5tac1 insertional mutations localized TRAX to a 14.8 kb segment containing the α origin of transfer (oriTα), genes involved in conjugative DNA-processing (DtrX) and genes involved in pilus synthesis and assembly (MpfX). A second functional oriT, oriTβ, was located at a distance of 5.3 kb from oriTα and was outside TRAX. MpfX occupied a segment of 10 kb, as judged by the location of insertions conferring resistance to infection by the X pilus-specific phage X-2. At both sides of MpfX there were insertions that were Tra− but X-2 sensitive, suggesting that the mutations were in DtrX. This region was sequenced and three genes were identified: taxA, taxB, and taxC. The overall organization was oriTα–taxA–taxC–MpfX–taxB. taxC coded for a oriT-relaxase that belongs to the VirD2 family. taxA coded for a protein of 181 amino acids that showed similarity to TraY of F-like plasmids and to the Arc-repressor superfamily. TaxB showed similarity to TraG-like proteins, a protein superfamily probably involved in coupling the relaxosome to the DNA-transport apparatus. TaxA and TaxC are required for oriT nicking in vivo. The nicking reaction was mistakenly assumed by Flashner et al. (1996) to represent a feature of the vegetative replication origins. However, insertions or deletions disrupting taxA and taxC affected conjugation but not replication of R6K. Conversely, protein π, which is absolutely required for replication of R6K, was not required for conjugative transfer. In addition, protein DDP3, which is also assumed to have a role in replication, was found to be a positive modulator of bacterial conjugation. Taken together, these results rule out a direct and essential involvement of conjugation proteins in R6K vegetative replication, and also rule out the requirement of replication protein π for conjugation.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 31 (1999), S. 0 
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: Relaxosomes are specific nucleoprotein structures involved in DNA-processing reactions during bacterial conjugation. In this work, we present evidence indicating that plasmid R388 relaxosomes are composed of origin of transfer (oriT) DNA plus three proteins TrwC relaxase, TrwA nic-cleavage accessory protein and integration host factor (IHF), which acts as a regulatory protein. Protein IHF bound to two sites (ihfA and ihfB) in R388 oriT, as shown by gel retardation and DNase I footprinting analysis. IHF binding in vitro was found to inhibit nic-cleavage, but not TrwC binding to supercoiled DNA. However, no differences in the frequency of R388 conjugation were found between IHF− and IHF+ donor strains. In contrast, examination of plasmid DNA obtained from IHF− strains revealed that R388 was obtained mostly in relaxed form from these strains, whereas it was mostly supercoiled in IHF+ strains. Thus, IHF could have an inhibitory role in the nic-cleavage reaction in vivo. It can be speculated that triggering of conjugative DNA processing during R388 conjugation can be mediated by IHF release from oriT.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...