In this study a second endogenous Porphyromonas gingivalis insertion element (IS element) that is capable of transposition within P. gingivalis was identified. Nucleotide sequence analysis of the Tn4351 insertion site in a P. gingivalis Tn4351-generated transconjugant showed that a complete copy of the previously unidentified IS element, designated PGIS2, had inserted into IS4351 R in Tn4351. PGIS2 is 1,207 bp in length with 19-bp imperfect terminal inverted repeats, and insertion resulted in a duplicated 10-bp target sequence. Results of Southern hybridization of chromosomal DNA isolated from several P. gingivalis strains with a PGIS2-specific probe demonstrated that the number of copies of PGIS2 per genome varies among different P. gingivalis strains. Computer analysis of the putative polypeptide encoded by PGIS2 revealed strong homologies to the products encoded by IS1358 from Vibrio cholerae, ISAS1 from Aeromonas salmonicida, and H-rpt in Escherichia coli K-12.Insertion elements (IS elements) are discrete genetic sequences capable of transposition to new locations within the prokaryotic chromosome, its bacteriophages, or its plasmids. These elements, which vary in size from 0.7 to 7.1 kilobase pairs (kb), contain little or no genetic information beyond that required for transposition. The terminal inverted repeats and duplicated target sequences are characteristic features for most IS elements. In spite of its relatively low frequency, transposition of IS elements is essential for their propagation and survival in a bacterial population (1). Transposition of IS elements also results in a number of genetic effects, including disruption of gene function, polarity effects, and activation of nearby genes or DNA rearrangements, all of which may contribute to the genetic diversity of a bacterial population (2).Porphyromonas gingivalis, an obligately anaerobic gram-negative cocobacillus, is an important pathogen in human periodontal disease. However, genetic analysis of P. gingivalis has been slow due to the lack of naturally occurring plasmids, bacteriophages, and efficient genetic transformation systems. Genco et al. (4) reported previously on the development of a transpositional mutagenesis system for P. gingivalis which uses Bacteroides fragilis transposon Tn4351. The high frequency of transposition, together with the observed stability of the insertion, indicated that Tn4351 mutagenesis would be a valuable tool for examining a variety of mutations in P. gingivalis. However, further characterization of P. gingivalis Tn4351 transconjugants indicated that Tn4351 had inserted 60 bp upstream from endogenous P. gingivalis IS element IS1126 (10). In addition, two additional copies of IS1126 were found in transconjugants compared to the wild-type strain, indicating that IS1126 was capable of mobilization in P. gingivalis (14). In this study, we have identified a second endogenous P. gingivalis IS element and have confirmed the transposition of this element within P. gingivalis. The new IS element, designated PGIS2, is...
Klebsiella pneumoniae is a common pathogen associated with nosocomial infections and is characterised serologically by capsular polysaccharide (K) and lipopolysaccharide O antigens. We surveyed a total of 348 non-duplicate K. pneumoniae clinical isolates collected over a 1-year period in a tertiary care hospital, and determined their O and K serotypes by sequencing of the wbb Y and wzi gene loci, respectively. Isolates were also screened for antimicrobial resistance and hypervirulent phenotypes; 94 (27.0%) were identified as carbapenem-resistant (CRKP) and 110 (31.6%) as hypervirulent (hvKP). isolates fell into 58 K, and six O types, with 92.0% and 94.2% typeability, respectively. The predominant K types were K14K64 (16.38%), K1 (14.66%), K2 (8.05%) and K57 (5.46%), while O1 (46%), O2a (27.9%) and O3 (11.8%) were the most common. CRKP and hvKP strains had different serotype distributions with O2a:K14K64 (41.0%) being the most frequent among CRKP, and O1:K1 (26.4%) and O1:K2 (17.3%) among hvKP strains. Serotyping by gene sequencing proved to be a useful tool to inform the clinical epidemiology of K. pneumoniae infections and provides valuable data relevant to vaccine design.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.