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Journal of Bacteriology, August 2001, p. 4718-4726, Vol. 183, No. 16
Department of Medical Microbiology and
Immunology, University of Wisconsin
Received 5 February 2001/Accepted 24 May 2001
We created plasmids for use in insertion-duplication mutagenesis
(IDM) of Neisseria gonorrhoeae. This mutagenesis method has the advantage that it requires only a single cloning step prior to
transformation into gonococci. Chromosomal DNA cloned into the plasmid
directs insertion into the chromosome at the site of homology by a
single-crossover (Campbell-type) recombination event. Two of the
vectors contain an erythromycin resistance gene, ermC, with
a strong promoter and in an orientation such that transcription will
proceed into the cloned insert. Thus, these plasmids can be used to
create insertions that are effectively nonpolar on the transcription of
downstream genes. In addition to the improved ermC, the
vector contains two copies of the neisserial DNA uptake sequence to
facilitate high-frequency DNA uptake during transformation. Using
various chromosomal DNA insert sizes, we have determined that even
small inserts can target insertion mutation by this method and that the
insertions are stably maintained in the gonococcal chromosome. We have
used IDM to create knockouts in two genes in the gonococcal genetic
island (GGI) and to clone additional regions of the GGI by a
chromosome-walking procedure. Phenotypic characterization of
traG and traH mutants suggests a role for the
encoded proteins in DNA secretion by a novel type IV secretion system.
0021-9193/01/$04.00+0 DOI: 10.1128/JB.183.16.4718-4726.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Insertion-Duplication Mutagenesis of
Neisseria: Use in Characterization of DNA Transfer Genes in
the Gonococcal Genetic Island
Madison Medical School,
Madison, Wisconsin 53706
*
Corresponding author. Mailing address: 1300 University
Ave., 471A MSC, Madison, WI 53706. Phone: (608) 265-2837. Fax: (608) 262-8418. E-mail: jpdillard{at}facstaff.wisc.edu.
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