Dataset Information

Lateral gene transfer of streptococcal ICE element RD2 (region of difference 2) encoding secreted proteins.

ABSTRACT:

Background

The genome of serotype M28 group A Streptococcus (GAS) strain MGAS6180 contains a novel genetic element named Region of Difference 2 (RD2) that encodes seven putative secreted extracellular proteins. RD2 is present in all serotype M28 strains and strains of several other GAS serotypes associated with female urogenital infections. We show here that the GAS RD2 element is present in strain MGAS6180 both as an integrative chromosomal form and a circular extrachromosomal element. RD2-like regions were identified in publicly available genome sequences of strains representing three of the five major group B streptococcal serotypes causing human disease. Ten RD2-encoded proteins have significant similarity to proteins involved in conjugative transfer of Streptococcus thermophilus integrative chromosomal elements (ICEs).

Results

We transferred RD2 from GAS strain MGAS6180 (serotype M28) to serotype M1 and M4 GAS strains by filter mating. The copy number of the RD2 element was rapidly and significantly increased following treatment of strain MGAS6180 with mitomycin C, a DNA damaging agent. Using a PCR-based method, we also identified RD2-like regions in multiple group C and G strains of Streptococcus dysgalactiae subsp.equisimilis cultured from invasive human infections.

Conclusions

Taken together, the data indicate that the RD2 element has disseminated by lateral gene transfer to genetically diverse strains of human-pathogenic streptococci.

SUBMITTER: Sitkiewicz I

PROVIDER: S-EPMC3083328 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Publications

Lateral gene transfer of streptococcal ICE element RD2 (region of difference 2) encoding secreted proteins.

Sitkiewicz Izabela I Green Nicole M NM Guo Nina N Mereghetti Laurent L Musser James M JM

BMC microbiology 20110401

<h4>Background</h4>The genome of serotype M28 group A Streptococcus (GAS) strain MGAS6180 contains a novel genetic element named Region of Difference 2 (RD2) that encodes seven putative secreted extracellular proteins. RD2 is present in all serotype M28 strains and strains of several other GAS serotypes associated with female urogenital infections. We show here that the GAS RD2 element is present in strain MGAS6180 both as an integrative chromosomal form and a circular extrachromosomal element. ...[more]

PMID: 21457552

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Project description:Streptococcus agalactiae or Group B Streptococcus (GBS) are opportunistic bacteria that can cause lethal sepsis in children and immuno-compromised patients. Their genome is a reservoir of mobile genetic elements that can be horizontally transferred. Among them, integrative and conjugative elements (ICEs) and the smaller integrative and mobilizable elements (IMEs) primarily reside in the bacterial chromosome, yet have the ability to be transferred between cells by conjugation. ICEs and IMEs are therefore a source of genetic variability that participates in the spread of antibiotic resistance. Although IMEs seem to be the most prevalent class of elements transferable by conjugation, they are poorly known. Here, we have studied a GBS-IME, termed IMESag-rpsI, which is widely distributed in GBS despite not carrying any apparent virulence trait. Analyses of 240 whole genomes showed that IMESag-rpsI is present in approximately 47% of the genomes, has a roughly constant size (approx. 9 kb) and is always integrated at a single location, the 3'-end of the gene encoding the ribosomal protein S9 (rpsI). Based on their genetic variation, several IMESag-rpsI types were defined (A-J) and classified in clonal complexes (CCs). CC1 was the most populated by IMESag-rpsI (more than 95%), mostly of type-A (71%). One CC1 strain (S. agalactiae HRC) was deep-sequenced to understand the rationale underlying type-A IMESag-rpsI enrichment in GBS. Thirteen open reading frames were identified, one of them encoding a protein (MobSag) belonging to the broadly distributed family of relaxases MOBV1 Protein MobSag was purified and, by a newly developed method, shown to cleave DNA at a specific dinucleotide. The S. agalactiae HRC-IMESag-rpsI is able to excise from the chromosome, as shown by the presence of circular intermediates, and it harbours a fully functional mobilization module. Further, the mobSag gene encoded by this mobile element is able to promote plasmid transfer among pneumococcal strains, suggesting that MobSag facilitates the spread of IMESag-rpsI and that this spread would explain the presence of the same IMESag-rpsI type in GBS strains belonging to different CCs.

Dataset Information

Lateral gene transfer of streptococcal ICE element RD2 (region of difference 2) encoding secreted proteins.

Background

Results

Conclusions

Publications

Lateral gene transfer of streptococcal ICE element RD2 (region of difference 2) encoding secreted proteins.

Similar Datasets

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