Affiliation:
1. Department of Periodontics1 and
2. Philips Institute of Oral and Craniofacial Molecular Biology,2Virginia Commonwealth University, Richmond, Virginia 23298;
3. The Institute for Genomic Research, Rockville, Maryland 208503; and
4. The Forsyth Institute, Boston, Massachusetts 021154
Abstract
ABSTRACT
Porphyromonas gingivalis
, a black-pigmented, gram-negative anaerobe, is found in periodontitis lesions, and its presence in subgingival plaque significantly increases the risk for periodontitis. In contrast to many bacterial pathogens,
P. gingivalis
strains display considerable variability, which is likely due to genetic exchange and intragenomic changes. To explore the latter possibility, we have studied the occurrence of insertion sequence (IS)-like elements in
P. gingivalis
W83 by utilizing a convenient and rapid method of capturing IS-like sequences and through analysis of the genome sequence of
P. gingivalis
strain W83. We adapted the method of Matsutani et al. (S. Matsutani, H. Ohtsubo, Y. Maeda, and E. Ohtsubo, J. Mol. Biol. 196:445–455, 1987) to isolate and clone rapidly annealing DNA sequences characteristic of repetitive regions within a genome. We show that in
P. gingivalis
strain W83, such sequences include (i) nucleotide sequence with homology to tRNA genes, (ii) a previously described IS element, and (iii) a novel IS-like element. Analysis of the
P. gingivalis
genome sequence for the distribution of the least used tetranucleotide, CTAG, identified regions in many of the initial 218 contigs which contained CTAG clusters. Examination of these CTAG clusters led to the discovery of 11 copies of the same novel IS-like element identified by the repeated sequence capture method of Matsutani et al. This new 1,512-bp IS-like element, designated IS
Pg5
, has features of the IS
3
family of IS elements. When a recombinant plasmid containing much of IS
Pg5
was used in Southern analysis of several
P. gingivalis
strains, including clinical isolates, diversity among strains was apparent. This suggests that IS
Pg5
and other IS elements may contribute to strain diversity and can be used for strain fingerprinting.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
15 articles.
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