Structure and function of conjugative pili: inducible synthesis of functional F pili by Escherichia coli K-12 containing a lac-tra operon fusion
| Autor: | P M Silverman, T H Grossman |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
biology
Operon Restriction Mapping lac operon medicine.disease_cause biology.organism_classification Microbiology Molecular biology Pilus Bacteriophage F Factor Microscopy Electron Plasmid Genes Bacterial Conjugation Genetic Fimbriae Bacterial medicine Escherichia coli Cloning Molecular Molecular Biology In vitro recombination Regulator gene Research Article |
| Zdroj: | Journal of bacteriology. 171(2) |
| ISSN: | 0021-9193 |
| Popis: | In vivo and in vitro recombination methods were used to construct the recombinant plasmid pTG801, in which the F-plasmid DNA transfer (tra) genes required for the formation of functional F pili were placed under the lac transcriptional control sequences of pUC19. The 20 kilobases of cloned F DNA includes genes traA through the 5'-terminal part of traG; the plasmid lacks the positive regulatory gene traJ and all of the known tra genes required for the DNA transfer stage of conjugation. pTG801 transformants were sensitive to the donor-specific bacteriophages Q beta and f1, as measured by the formation of infectious centers. They were relatively insensitive to bacteriophage R17, as expected from the absence of traD. In the presence of a lacIq allele, sensitivity of pTG801 transformants to f1 and Q beta depended on the concentration of inducer (isopropyl-beta-D-thiogalactopyranoside [IPTG]). Viewed by electron microscopy, pTG801 transformants elaborated 7- to 10-nm-diameter filaments that could be laterally decorated with RNA bacteriophage particles, consistent with the formation of F pili. In stationary-phase cultures, these filaments formed massive aggregates and could be seen to adhere lengthwise to the cell surface; few pili accumulated in the medium as single filaments. |
| Databáze: | OpenAIRE |
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