Publication details

Genome analysis of staphylococcal exfoliative toxin A converting bacteriophages



Year of publication 2008
Type Article in Proceedings
Conference XII. Setkání biochemiků a molekulárních biologů
MU Faculty or unit

Faculty of Science

Field Genetics and molecular biology
Keywords Staphylococcus aureus; exfoliative toxin A; converting phage
Description Introduction: The exfoliative toxin A (ETA) is coded by the eta gene of S. aureus prophage. We isolated three eta-positive phages from the clinical S. aureus strains. ETA-negative strain SAU1039 was lysogenized by these phages and was converted into a producer of ETA. Our results indicate that ETA-converting B phages that morphologically resemble the phages of the family Siphoviridae seem to be the major mediators of the eta gene horizontal transfer among the S. aureus strains. We also found that the eta-positive A phage transposed the eta gene into recipient strain, but the lysogens were not able to produce the ETA. On the basis of genomic sequence analysis and alignments both the converting B phages were found to be equal but they differed from the eta-positive A phage in some characteristics. Methods: PCR detection of integrase types and DNA regions: integrase (int), terminase (ter), portal protein (por), holin (hol) amidase (ami), and exfoliative toxin A (eta) genes. Sequencing of target genes, genomic regions or two conservative segments (H3 and H4).Comparative genomics of A and B phages based on sequence studies. Comparison with known sequences of Staphylococcus phages accessible from bioinformatics sources. Results: We carried out the molecular analysis of three ETA-converting phages, i.e. serotype A like phi435 and two serotype B like phages designated phi531 and phi557. We focused our attention on the int, ter, por, hol, ami and eta genes, and two conservative segments H3 and H4 located on two HindIII restriction fragments. On the basis of analyses of target sequences we found out the high sequence similarity between the eta-positive B phages from our region and the Japanese phage phiETA (GenBank acc. no. AP001553). The A phage showed the gene sequence similarities with B phages but differed from them in two genomic regions, the por gene and H4 segment. Conclusions: We found the high sequence similarity in studied genome regions between our ETA-converting B phages and the reference ETA-converting phage phiETA (GenBank acc. no. AP001553) but they showed some genomic differences from the eta-positive A phage. The manner how the A phage has acquired the eta gene remains to be elucidated.
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