AP200 has been previously reported to harbour the transposon Tn1806, carrying the erythromycin resistance determinant erm(TR), which is uncommon in S. pneumoniae Selleck 4SC-202 . The genome sequence yielded the whole sequence of Tn1806 and evidence for the presence of another exogenous element, a functional bacteriophage, designated ϕSpn_200. Results and Discussion General genome features The AP200 chromosome is circular and is 2,130,580 base
pair in length. The main features of the sequence are shown in Figure 1 and Table 1.The initiation codon of the dnaA gene, adjacent to the origin of replication oriC, was chosen as the base pair 1 for numbering the coding sequences. The overall GC% content is 39.5% but an unusual asymmetry in the GC skew is evident near positions 820,000-870,000, likely resulting from recent acquisitions through horizontal gene transfer. The genome carries 2216 coding sequences (CDS), 56 tRNA, and 12 rRNA genes grouped in four operons. Of the predicted CDSs, 1616 (72.9%) have a predicted biological known function; 145 (6.5%) are similar to hypothetical proteins in other genomes, and 455 (20.5%) APR-246 chemical structure have no substantial
similarity to other predicted proteins. Figure 1 Circular representation of S. pneumoniae AP200 chromosome. Outer circle: distribution of the exogenous elements ϕSpn_200 and Tn1806 (dark blue). Second and third circles: predicted coding sequences on the plus and minus strand, respectively. Each circle has been divided in 4 rings according to the predicted functions:(from outer to inner ring) proteins poorly characterized, proteins involved in metabolism, proteins involved in information, storage and processing, proteins ID-8 involved in cellular processes. Fourth circle: GC content. Fifth circle: GC deviation. Sixth and seventh circles: tRNA (dark green) and rRNA (red) on the plus and minus strand, respectively. Table 1 General
find more characteristics of the S. pneumoniae AP200 genome. Component of the genome Property Topology Circular Length 2,130,580 bp G+C content 39.5% Coding density 86.1% Coding sequences 2,283 rRNA 12 genes in four sets tRNA 56 CDS 2,216 conserved with assigned function 1,616 (72.9%) conserved with unknown function 145 (6.5%) nonconserved 455 (20.5%) Average CDS length 828 bp Exogenous elements ΦSpn_200 35,989 bp Tn1806 52,457 bp IS1239 10 copies IS1381-ISSpn7 9 copies IS1515 8 copies ISSpn2 and IS1167 6 copies each IS630, ISSpn1-3 and IS1380- ISSpn5 4 copies each IS1202 1 copy ISSpn_AP200_1 to ISSpn_AP200_7 1 to 3 copies The AP200 genome contains approximately 170 kb that are not present in TIGR4 [GenBank: NC_010380], the first sequenced pneumococcal strain . Besides two exogenous elements, such as the large Tn1806 transposon and a temperate bacteriophage designated ϕSpn_200, the extra regions include the type 11A capsular locus, the pilus islet 2 , and two metabolic operons (Additional file 1).