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J Bacteriol. 2007 Mar;189(5):2077-85. Epub 2006 Dec 28.

New functional identity for the DNA uptake sequence in transformation and its presence in transcriptional terminators.

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  • 1Institute of Microbiology and Centre for Molecular Biology and Neuroscience, University of Oslo, Rikshospitalet-Radiumhospitalet Medical Center, NO-0027 Oslo, Norway.

Abstract

The frequently occurring DNA uptake sequence (DUS), recognized as a 10-bp repeat, is required for efficient genetic transformation in the human pathogens Neisseria meningitidis and Neisseria gonorrhoeae. Genome scanning for DUS occurrences in three different species of Neisseria demonstrated that 76% of the nearly 2,000 neisserial DUS were found to have two semiconserved base pairs extending from the 5' end of DUS to constitute a 12-mer repeat. Plasmids containing sequential variants of the neisserial DUS were tested for their ability to transform N. meningitidis and N. gonorrhoeae, and the 12-mer was found to outperform the 10-mer DUS in transformation efficiency. Assessment of meningococcal uptake of DNA confirmed the enhanced performance of the 12-mer compared to the 10-mer DUS. An inverted repeat DUS was not more efficient in transformation than DNA species containing a single or direct repeat DUS. Genome-wide analysis revealed that half of the nearly 1,500 12-mer DUS are arranged as inverted repeats predicted to be involved in rho-independent transcriptional termination or attenuation. The distribution of the uptake signal sequence required for transformation in the Pasteurellaceae was also biased towards transcriptional terminators, although to a lesser extent. In addition to assessing the intergenic location of DUS, we propose that the 10-mer identity of DUS should be extended and recognized as a 12-mer DUS. The dual role of DUS in transformation and as a structural component on RNA affecting transcription makes this a relevant model system for assessing significant roles of repeat sequences in biology.

PMID:
17194793
[PubMed - indexed for MEDLINE]
PMCID:
PMC1855724
Free PMC Article

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