Repository logo
 

Insertional activation of cepA leads to high-level beta-lactamase expression in Bacteroides fragilis clinical isolates.

dc.contributor.authorRogers, Marc B.en_US
dc.contributor.authorBennett, Tamara K.en_US
dc.contributor.authorPayne, Catherine M.en_US
dc.contributor.authorSmith, C. Jeffreyen_US
dc.date.accessioned2011-04-28T14:43:00Zen_US
dc.date.accessioned2011-05-17T01:40:10Z
dc.date.available2011-04-28T14:43:00Zen_US
dc.date.available2011-05-17T01:40:10Z
dc.date.issued1994-07en_US
dc.description.abstractBacteroides fragilis is an important opportunistic pathogen of humans and is resistant to many drugs commonly used to treat anaerobic infections, including P-lactams. A strain set comprised of B. fragilis isolates producing either low or high levels of the endogenous cephalosporinase activity, CepA, has been described previously (M. B. Rogers, A. C. Parker, and C. J. Smith, Antimicrob. Agents Chemother. 37:2391-2400, 1993). Clones containing cepA genes from each of seven representative strains were isolated, and the DNA sequences were determined. Nucleotide sequence comparisons revealed that there were few differences between the cepA coding sequences of the low- and high-activity strains. The cepA coding sequences were cloned into an expression vector, pFD340, and analyzed in a B.fragilis 638 cepA mutant. The results of j-lactamase assays and ampicillin MICs showed that there was no significant difference in the enzymatic activity of structural genes from the high- or low-activity strains. Comparison of sequences upstream of the cepA coding region revealed that 50 bp prior to the translation start codon, the sequence for high-activity strains change dramatically. This region of the high-activity strains shared extensive homology with IS21, suggesting that an insertion was responsible for the increased expression of cepA in these isolates. Northern (RNA) blot analysis of total RNA by using cepA-specific DNA probes supported the idea that differential cepA expression in low- and high-activity strains was controlled at the level of transcription. However, the insertion did not alter the cepA transcription start site, which occurred 27 bp upstream of the ATG translation start codon in both expression classes. Possible mechanisms of cepA activation are discussed. Originally published Journal of Bacteriology, Vol. 176, No. 14, July 1994en_US
dc.identifier.citationJournal of Bacteriology; 176:14 p. 4376-4384en_US
dc.identifier.pmidPMC205651en_US
dc.identifier.urihttp://hdl.handle.net/10342/3379en_US
dc.language.isoen_USen_US
dc.publisherEast Carolina Universityen_US
dc.relation.urihttp://jb.asm.org/archive/1994.dtlen_US
dc.rightsAuthor notified of opt-out rights by Cammie Jennings prior to upload of this article.en_US
dc.subjectBacteroides fragilisen_US
dc.subjectCepAen_US
dc.subjectBeta-lactamaseen_US
dc.titleInsertional activation of cepA leads to high-level beta-lactamase expression in Bacteroides fragilis clinical isolates.en_US
dc.typeArticleen_US
ecu.journal.issue14
ecu.journal.nameJournal of Bacteriology
ecu.journal.pages4376-4384
ecu.journal.volume176

Files

Original bundle

Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
Insertional activation of cepA.pdf
Size:
2.04 MB
Format:
Adobe Portable Document Format