The Transcriptional landscape of Streptococcus pneumoniae TIGR4 reveals a complex operon architecture and abundant riboregulation critical for growth and virulence
Fig 4
Variability in expression levels between genes in the same operon when grown in rich (SDMM) and poor (MCDM) media conditions.
RNA-Seq coverage maps of complex operon/regulon including the TSSs in green and TTSs in red. Size of the transcriptional features represents log transformation of the processed/unprocessed ratio for TSSs and coverage for TTSs. Arrows on the TSS represent the strand and direction of transcription. There are little to no reads mapped to the strand opposite to coding regions. Coverage was normalized to the number of uniquely mapped reads in each library and log10 transformed for representation (A) A complex 9-gene operon (SP_1018–SP_1026) encoding thymidine kinase, GNAT family N-acetyltransferase, peptide chain release factor 1, peptide chain release factor N(5)-glutamine methyltransferase, threonylcarbomyl-AMP synthase, N-acetyltransferase, serine hydroxymethyltransferase, nucleoid-associated protein, and Pneumococcal vaccine antigen A respectively. Genes SP_1022-SP_1026 are expressed to greater levels in MCDM than in SDMM unlike genes SP_1018-SP_1021. (B) The maltose regulon, an example of two operons of different complexities working together in response to maltose in the medium. Complex operon SP_2108-SP_2112 shows greater expression in MCDM than SDMM in comparison to the multiTTS operon SP_2106-SP_2017.