Streptococcus pneumoniae is an important human pathogen that causes a variety of diseases, such as pneumonia, bacteremia, meningitis, otitis media, and sinusitis, in both adults and children. The global pattern of growth phase-dependent protein expression of S. pneumoniae during in vitro culture was analyzed using 2-DE combined with MALDI-TOF MS and LC/ESI-MS/MS. Several protein production patterns were observed at four time points throughout the growth stage, although some protein levels did not change significantly. We focused on the switch in protein expression at the transition from log growth phase to stationary phase. Proteins that were significantly induced or repressed at this point are likely to be involved in central intermediary metabolism, amino acid synthesis, nucleotide, and fatty acid metabolism, cell wall synthesis, protein degradation, and stress responses. This global expression profiling approach has revealed previously unrecognized relationships between proteins in the life of this pathogen.
Sphingobium chungbukense DJ77 is capable of metabolizing priority chemicals of human health concern such as polycyclic aromatic hydrocarbons (PAHs), extracellular polysaccharide (EPS), and antibiotics. Here, we report the complete DNA and genetic organization of the plasmid pSY2 from strain DJ77. A DNA sequence analysis revealed that pSY2 comprises 18,779 bp encoding 22 open reading frames (ORFs) with 59.5% G+C content. The ORFs on pSY2 were classified into DNA replication, conjugative function, transposition, plasmid stability/partition, and other functional groups (transport, fatty acid biosynthesis, stress, and growth rate regulation). Three ORFs on pSY2 were hypothetical proteins.
The nucleotide sequences of all three rRNA operons (rrnA, rrnB, and rrnC) of Sphingobium chungbukense DJ77 were determined. The three rrn operons have the same gene order (16S rRNA-tRNAIle-tRNAAla-23S rRNA-5S rRNA-tRNAfMet). The nucleotide sequences were identical over a 5,468 bp region spanning the 16S rRNA gene to the 5S rRNA gene. Variability was observed in the 5S rRNA-tRNAfMet spacer sequence of rrnB. The tRNAfMet gene sequences were identical except for two bases (T5794 and A5871 in rrnB, T5942 and A5956 in rrnA, but C5942 and G5956 in rrnC). Comparative sequence analyses of ribosomal RNA operons from DJ77 with those of the class Alphaproteobacteria, to which the genus Sphingobium belongs, reveal close evolutionary relationships with other members of the order Sphingomonadales.
This study determined the complete nucleotide sequence of the plasmid pSY3 from Sphingobium chungbukense DJ77. It was 35,735 bp long with a G+C content of 61.9%. Forty open reading frames (ORFs) were found. We predicted these ORFs would encode proteins associated with plasmid replication, conjugative transfer, transposition of genes, plasmid stability/partition, hypothetical protein, and some other functions. Genes for biodegradation were not found. No other plasmid homologous to pSY3 in the overall nucleotide sequence or gene organization could be found in the NCBI database.
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