NAR：中科院、首都医科大新成果单分子测序的精确甲基化组分析

摘要 : 日前，在Nucleic acid research杂志上，由中科院、首都医科大等机构的研究人员对MTBC进行了深入研究。他们发现，单分子实时测序可以实现精确的甲基化组分析。这项研究说明，SMRT平台在甲基化组精确分析上很有潜力，能显著增强我们对DNA MTase功能的了解。

日前，在Nucleic acid research杂志上，由中科院、首都医科大等机构的研究人员对MTBC进行了深入研究。他们发现，单分子实时测序可以实现精确的甲基化组分析。这项研究说明，SMRT平台在甲基化组精确分析上很有潜力，能显著增强我们对DNA MTase功能的了解。

肺结核(TB)是结核分枝杆菌复合群(MTBC)造成的常见传染病。现有抗生素能够缓解肺结核的症状，但治疗往往持续数月而且还无法将其完全根除，导致这种疾病在治疗数年后频频复发。

中科院、首都医科大等机构的研究人员对MTBC进行了深入研究。他们发现，单分子实时测序可以实现精确的甲基化组分析。这项研究发表在前不久的Nucleic acid research杂志上，文章的通讯作者是中科院北京基因组研究所的陈非和首都医科大学附属北京胸科医院的黄海荣。

为了全面了解MTBC的基因组甲基化，研究人员采用PacBio的单分子实时测序技术(SMRT)完成了12个MTBC菌株的基因组，并且分析了它们甲基化组的特征。研究人员鉴定了三个m6A序列模体及其相应的甲基转移酶(MTase)基因，包括已知的mamA、hsdM和新发现的mamB。他们还通过实验验证了HsdM和MamB的甲基化模体和功能。

研究显示，上述12种菌的MTase活性并不相同。单分子测序可以揭示每个修饰位点的甲基化状态，得出特定MTBC菌株的精确甲基化组。未修饰的位点大多与转录因子的结合区域重叠，这可能为这些位点提供了保护，使其不被甲基化。

原文链接：Precision methylome characterization of mycobacterium tuberculosis complex (MTBC) using PacBio single-molecule real-time (SMRT) technology

原文摘要：Tuberculosis (TB) remains one of the most common infectious diseases caused by Mycobacterium tuberculosis complex (MTBC). To panoramically analyze MTBC's genomic methylation, we completed the genomes of 12 MTBC strains (Mycobacterium bovis; M. bovis BCG; M. microti; M. africanum; M. tuberculosis H37Rv; H37Ra; and 6 M. tuberculosis clinical isolates) belonging to different lineages and characterized their methylomes using single-molecule real-time (SMRT) technology. We identified three m6A sequence motifs and their corresponding methyltransferase (MTase) genes, including the reported mamA, hsdM and a newly discovered mamB. We also experimentally verified the methylated motifs and functions of HsdM and MamB. Our analysis indicated the MTase activities varied between 12 strains due to mutations/deletions. Furthermore, through measuring ‘the methylated-motif-site ratio’ and ‘the methylated-read ratio’, we explored the methylation status of each modified site and sequence-read to obtain the ‘precision methylome’ of the MTBC strains, which enabled intricate analysis of MTase activity at whole-genome scale. Most unmodified sites overlapped with transcription-factor binding-regions, which might protect these sites from methylation. Overall, our findings show enormous potential for the SMRT platform to investigate the precise character of methylome, and significantly enhance our understanding of the function of DNA MTase.

doi: 10.1093/nar/gkv1498

作者：阳光森林

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