PDF(Pubmed)
Abstract：
Bacterial virulence, persistence and defence are affected by epigenetic modifications, including DNA methylation. Solitary DNA methyltransferases modulate a variety of cellular processes and influence bacterial virulence; as part of a restriction-modification (RM) system, they act as a primitive immune system in methylating the own DNA, while unmethylated foreign DNA is restricted. We identified a large family of type II DNA methyltransferases in Metamycoplasma hominis, comprising six solitary methyltransferases and four RM systems. Motif-specific 5mC and 6mA methylations were identified with a tailored Tombo analysis on Nanopore reads. Selected motifs with methylation scores >0.5 fit with the gene presence of DAM1 and DAM2, DCM2, DCM3, and DCM6, but not for DCM1, whose activity was strain-dependent. The activity of DCM1 for CmCWGG and of both DAM1 and DAM2 for GmATC was proven in methylation-sensitive restriction and finally for recombinant rDCM1 and rDAM2 against a dam-, dcm-negative background. A hitherto unknown dcm8/dam3 gene fusion containing a (TA) repeat region of varying length was characterized within a single strain, suggesting the expression of DCM8/DAM3 phase variants. The combination of genetic, bioinformatics, and enzymatic approaches enabled the detection of a huge family of type II DNA MTases in M. hominis, whose involvement in virulence and defence can now be characterized in future work.
摘要：
细菌毒力,持久性和防御性受到表观遗传修饰的影响，包括DNA甲基化。孤立的DNA甲基转移酶调节各种细胞过程并影响细菌毒力;作为限制性修饰（RM）系统的一部分，它们作为一个原始的免疫系统在甲基化自己的DNA，而未甲基化的外源DNA受到限制。我们确定了一个大家族的II型DNA甲基转移酶在人型更生，包括六个孤立的甲基转移酶和四个RM系统。基序特异性5mC和6mA甲基化用对纳米孔读数的定制Tombo分析鉴定。甲基化评分>0.5的选定基序符合DAM1和DAM2，DCM2，DCM3和DCM6的基因存在，但不符合DCM1，DCM1的活性是菌株依赖性的。在甲基化敏感性限制中证明了DCM1对CmCWGG的活性以及DAM1和DAM2对GmATC的活性，最后证明了重组rDCM1和rDAM2对dam-，dcm-负背景。在单个菌株中表征了迄今为止未知的dcm8/dam3基因融合体，该融合体包含不同长度的（TA）重复区，提示DCM8/DAM3期变体的表达。遗传的结合，生物信息学，和酶的方法使得能够在人型支原体中检测到一个巨大的II型DNAMTases家族，他们参与毒力和防御现在可以在未来的工作中表征。
