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Composite structure of Streptococcus pneumoniae containing the erythromycin efflux resistance gene mefI and the chloramphenicol resistance gene catQ.

ABSTRACT: In recent years mef genes, encoding efflux pumps responsible for M-type macrolide resistance, have been investigated extensively for streptococci. mef(I) is a recently described mef variant detected in particular isolates of Streptococcus pneumoniae instead of the more common mef(E) and mef(A). This study shows that mef(I) is located in a new composite genetic element, whose sequence was completely analyzed and the left and right junctions determined, demonstrating a unique genetic organization. The new composite structure (30,505 bp), designated the 5216IQ complex, consists of two halves: a left one (15,316 bp) formed by parts of the known transposons Tn5252 and Tn916, and a right one (15,115 bp) formed by a new fragment, designated the IQ element. While the defective Tn916 contained a silent tet(M) gene, the IQ element, ending with identical transposase genes on both sides and containing the mef(I) gene with an adjacent new msr(D) gene variant and a catQ chloramphenicol acetyltransferase gene, was completely different from the genetic elements carrying other mef genes in pneumococci. This is the first report demonstrating catQ in S. pneumoniae and showing its linkage with a mef gene. Analysis of the chromosomal region beyond the left junction revealed an organization more similar to that of S. pneumoniae strain TIGR4 than to that of strain R6. The 5216IQ complex was apparently nonmobile, with no detectable transfer of erythromycin resistance being obtained in repeated transformation and conjugation assays.

SUBMITTER: Mingoia M

PROVIDER: S-EPMC2151433 | biostudies-literature | 2007 Nov

REPOSITORIES: biostudies-literature

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Composite structure of Streptococcus pneumoniae containing the erythromycin efflux resistance gene mefI and the chloramphenicol resistance gene catQ.

Mingoia Marina M Vecchi Manuela M Cochetti Ileana I Tili Emily E Vitali Luca A LA Manzin Aldo A Varaldo Pietro E PE Montanari Maria Pia MP

Antimicrobial agents and chemotherapy 20070820 11

In recent years mef genes, encoding efflux pumps responsible for M-type macrolide resistance, have been investigated extensively for streptococci. mef(I) is a recently described mef variant detected in particular isolates of Streptococcus pneumoniae instead of the more common mef(E) and mef(A). This study shows that mef(I) is located in a new composite genetic element, whose sequence was completely analyzed and the left and right junctions determined, demonstrating a unique genetic organization. ...[more]

PMID: 17709462

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Project description:Streptococcus pneumoniae is a Gram positive bacterium that causes severe invasive infection such as pneumonia, septicemia, meningitis and otitis media especially in children, the elderly and immune-compromised patients. Pneumococcal colonization and disease is often associated with biofilm formation. Bacteria in biofilms exhibit elevated resistance both to antibiotics and to host defense systems, which often results in persistent and difficult-to-treat infections. Therefore, the ongoing treat to human health posed by pneumococcal biofilms has prompted extensive research aimed to identify alternative targets and new antimicrobial agents that are effective against bacteria biofilms. The effective anti-biofilm strategies should include inhibition of microbial adhesion to the surface and of colonization, interference with the signal molecules modulating biofilm development and the disaggregation of the biofilm matrix. In this study, we examine the effect of DAM inhibitor small molecule pyrimidine-diones on streptococcus pneumoniae D-39 strain growth (planktonic and biofilm) and evaluate the changes in global gene expression using c-DNA microarray. The microarray analysis was performed on total RNA extracted from biofilms grown in 24-well microtiter plate with 7µm/ml pyrimidine-diones small molecule and control biofilms (biofilms grown without pyrimidine-diones small molecule). To validate the results of microarray, real-time RT-PCR was performed on 12 differentially expressed genes from six different functional groups. cDNA-microarray analysis detected a total of 259 genes that were significantly differentially expressed in biofilm growth with pyrimidine-diones small molecule. 204 genes were significantly down expressed and 55 genes were significantly up expressed in biofilms grown with 7µm/ml pyrimidine-diones small molecule. Among the 204 down expressed genes, 45 were hypothetical protein encoding gene and 159 were functional protein encoding genes. Of 55 up-regulated genes 21 were hypothetical genes and 34 were functional protein encoding genes. The functional annotation showed that gene involve in fatty acid metabolism, cell division, cell cycles, DNA metabolism, cell assembly were significantly down regulated and galactose metabolism related gene were up-expressed in biofilm grown with pyrimidine-diones small molecule.

Dataset Information

Composite structure of Streptococcus pneumoniae containing the erythromycin efflux resistance gene mefI and the chloramphenicol resistance gene catQ.

Publications

Composite structure of Streptococcus pneumoniae containing the erythromycin efflux resistance gene mefI and the chloramphenicol resistance gene catQ.

Similar Datasets

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