||Comparative genomic hybridization of Streptococcus mitis B6 and other Streptococcus mitis strains
||Genomic comparison of Streptococcus mitis B6 and other Streptococcus mitis strains
||Yvonne Schähle, Patrick Maurer
||Microarray-based transcription profiling of Streptococcus pneumoniae R6 ΔrgtA, ΔrgtD and ΔcpoA
||Alterations in genes for penicillin-binding proteins (pbp) are well-known determinants for the resistance of Streptococcus pneumoniae to B-lactam antibiotics. Surprisingly, some mutations in non-pbp genes were also found to contribute to β-lactam resistance. Two of them discovered in the piperacillin resistant mutants P106 and P104, affect the expression of cpoA (encoding a glycosyltransferase) and of the rgtABCDHR cluster (encoding two small membrane proteins, an ABC transporter and a regulatory two-component system), respectively. cpoA and rgtABCDHR are involved in maintaining the synthesis and the proper ratio of the two major membrane glycolipids, and deletions in these genes led to complex phenotypes. In attempts to identify genetic determinants for these phenotypes, the global trancription patterns of the deletion mutants R6 ΔcpoA, R6 ΔrgtA and R6 ΔrgtD were compared to that of the parent strain R6.
||Carsten Volz, Patrick Maurer
||CCCB - Genomic variation
||Antibiotic resistance in Streptococcus pneumoniae is often the result of horizontal gene transfer events involving closely related streptococcal species. Laboratory experiments confirmed that S. mitis DNA functions as donor in transformation experiments, using the laboratory strain S. pneumoniae R6 as recipient and chromosomal DNA of a high level penicillin resistant S. mitis B6 strain. After four transformation steps, alterations in five penicillin-binding proteins (PBP) were observed, and sequence analysis confirmed recombination events in the corresponding PBP genes. In order to detect regions where recombination with S. mitis DNA has occurred we analyzed the S. pneumoniae transformants by microarray analyses, using oligonucleotide microarrays designed for the S. pneumoniae genome and the S. mitis B6 genome as well.
||Julia Sauerbier, Patrick Maurer
||Pathochip of Streptococcus spp surface proteins
||In order to appreciate the presence of surface protein gene homologues in commensal species S. mitis and S. oralis, comparative genomic hybridization studies using DNA microarrays were performed with 8 S. mitis and 11 S. oralis from different geographic locations. The oligonucleotide microarray was designed based on the genomes of S. pneumoniae R6 and TIGR4 as well as S. mitis B6 to include genes of 63 cell surface proteins. The denatured genomic DNA of the S. mitis and S. oralis strains was labeled with Cy3-dCTP and control S. mitis B6 DNA was labeled with Cy5-dCTP. Hybridization was performed following the manufacturers recommendations using an hybridization temperature of 40°C for 16 h. For data processing, microarrays were scanned on the laser scanner Pro Scan Array GX (PerkinElmer) with the low resolution of 50 µm using ScanArrayExpress Software version 4.0. Photomultiplier tube was adjusted to balance the two fluorescence channels and biochips were scanned with a resolution of 10 µm. After elimination of background values fluorescence intensity was determined. Signals that showed an intensity ratio of 0.3 and above were considered to be positive.
||Abderrahim Madhour, Patrick Maurer
||Transcription profiling by array of Streptococcus pneumoniae Cefotaxime resistant R6 mutants containing mutations in pbp2x, ciaH, pbp2a and mutants with different mosaic pbp2x, pbp1a genes
||Investigation of transcription profile of spontaneous Cefotaxime resistant R6 mutants containing mutations in pbp2x, ciaH, pbp2a and mutants with different mosaic pbp2x, pbp1a genes.
||Ilka Zerfass, Patrick Maurer