Transcriptomic comparison of D39 WT and SPD_0588 deletion mutant in Streptococcus pneumoniae D39 with 1 µg/ml methionine

metR (SPD_0588) mutant (TH9197) cannot grow in chemically defined medium (CDM) without methionine and had significant growth defect in CDM with 1 µg/ml methionine. With the increasing concentration of mehtionine, the growth of TH9197 was restored and the growth of metR mutant is as same as D39 WT (TH4306) when the concentration of methionine reaches 50 µg/ml. SPD_0588 is a putative transcriptional regulator and is homologous to MetR in Streptococcus mutans (78.9 % amino acid identity), which regulates both methionine synthesis and transport. We compared the transcriptome of WT and metR mutant in CDM with 1 µg/ml methionine by RNA-seq to see if MetR regulates the metabolism of methionine in Streptococcus pneumoniae D39. We also want to identify the regulon of SPD_0588. Transcriptome comparison of D39 WT and metR mutant in CDM with 1 µg/ml methionine. It was done by deep sequencing, using Miseq instrument with 101 nt paired-end reads.

metR（SPD_0588）突变体（TH9197）无法在不含甲硫氨酸（methionine）的化学成分确定培养基（chemically defined medium，CDM）中生长，且在添加1 µg/ml甲硫氨酸的CDM中存在显著生长缺陷。随着甲硫氨酸浓度升高，TH9197的生长缺陷得以修复；当甲硫氨酸浓度达到50 µg/ml时，metR突变体的生长水平与D39野生型菌株（TH4306）完全一致。SPD_0588为推定的转录调控因子，与变形链球菌（Streptococcus mutans）中的MetR蛋白具有同源性（氨基酸一致性达78.9%），其可同时调控甲硫氨酸的合成与转运过程。为探究MetR是否调控肺炎链球菌D39（Streptococcus pneumoniae D39）的甲硫氨酸代谢，我们通过RNA测序（RNA-seq）比较了在添加1 µg/ml甲硫氨酸的CDM中野生型菌株与metR突变体的转录组。同时，本研究还旨在鉴定SPD_0588的调控子（regulon）。本次转录组比较分析采用深度测序（deep sequencing）技术完成，使用MiSeq测序仪（Miseq instrument）进行测序，测序读段为101 nt双端测序读段（paired-end reads）。