JB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Twomey, D. P.
Right arrow Articles by O'Sullivan, D. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Twomey, D. P.
Right arrow Articles by O'Sullivan, D. J.

 Previous Article  |  Next Article 

Journal of Bacteriology, November 1998, p. 5844-5854, Vol. 180, No. 22
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.

Molecular Characterization of the Lactococcus lactis LlaKR2I Restriction-Modification System and Effect of an IS982 Element Positioned between the Restriction and Modification Genesdagger

Denis P. Twomey,Dagger Larry L. McKay, and Daniel J. O'Sullivan*

Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108

Received 6 March 1998/Accepted 4 September 1998

The nucleotide sequence of the plasmid-encoded LlaKR2I restriction-modification (R-M) system of Lactococcus lactis subsp. lactis biovar diacetylactis KR2 was determined. This R-M system comprises divergently transcribed endonuclease (llaKR2IR) and methyltransferase (llaKR2IM) genes; located in the intergenic region is a copy of the insertion element IS982, whose putative transposase gene is codirectionally transcribed with llaKR2IM. The deduced sequence of the LlaKR2I endonuclease shared homology with the type II endonuclease Sau3AI and with the MutH mismatch repair protein, both of which recognize and cleave the sequence 5' GATC 3'. In addition, M · LlaKR2I displayed homology with the 5-methylcytosine methyltransferase family of proteins, exhibiting greatest identity with M · Sau3AI. Both of these proteins shared notable homology throughout their putative target recognition domains. Furthermore, subclones of the native parental lactococcal plasmid pKR223, which encode M · LlaKR2I, all remained undigested after treatment with Sau3AI despite the presence of multiple 5' GATC 3' sites. The combination of these data suggested that the specificity of the LlaKR2I R-M system was likely to be 5' GATC 3', with the cytosine residue being modified to 5-methylcytosine. The IS982 element located within the LlaKR2I R-M system contained at its extremities two 16-bp perfect inverted repeats flanked by two 7-bp direct repeats. A perfect extended promoter consensus, which represented the likely original promoter of the llaKR2IR gene, was shown to overlap the direct repeat sequence on the other side of IS982. Specific deletion of IS982 and one of these direct repeats via a PCR strategy indicated that the LlaKR2I R-M determinants do not rely on elements within IS982 for expression and that the efficiency of bacteriophage restriction was not impaired.

* Corresponding author. Mailing address: Department of Food Science and Nutrition, 1334 Eckles Ave., St. Paul, MN 55108. Phone: (612) 624-5335. Fax: (612) 625-5272. E-mail: osull001{at}tc.umn.edu.

dagger Paper no. 981180025 of the Scientific Journal Series of the Minnesota Agricultural Experiment Station.

Dagger Present address: Dairy Quality Department, Teagasc, National Dairy Products Research Center, Moorepark, Fermoy, Co. Cork, Ireland.

Journal of Bacteriology, November 1998, p. 5844-5854, Vol. 180, No. 22
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 1998 by the American Society for Microbiology. All rights reserved.