Laboratoire Adaptation et Pathogénie des Micro-organismes, CNRS UMR 5163 - ATIP+ Group, Université Joseph Fourier, BP 170, F-38042 Grenoble cedex 9, France.
Cell Microbiol. 2010 Apr 1;12(4):413-23. doi: 10.1111/j.1462-5822.2010.01446.x. Epub 2010 Jan 26.
The apicomplexan Toxoplasma gondii completes its life cycle by successive processes of parasite differentiation that rely on a tight control of gene expression to ensure appropriate protein profiles on time. During the last 5 years, several groups have pioneered this field of investigation, suggesting that epigenetics could play an important role in the control of parasite gene expression. Histone modifications serve as an effective way to regulate gene transcription but they do not operate alone; rather, they act in concert with other putative epigenetic information carriers (histone variants, small RNAs) and DNA sequence-specific transcription factors to modulate the higher-order structure of the chromatin fibre and govern the on-time recruitment of the transcriptional machinery to specific genes. Regarding the 'histone code' hypothesis, the parasite is endowed with a rich repertoire of histone-modifying enzymes catalysing site-selective modifications, which are subsequently interpreted by effector proteins that recognize specific covalent marks. Still, several peculiarities seem unique to T. gondii. This review is a synthesis of the current knowledge of how epigenetics contribute to the control of gene expression in T. gondii and, likely, other Apicomplexa.
刚地弓形虫通过寄生虫分化的连续过程完成其生命周期，这依赖于对基因表达的严格控制，以确保及时获得适当的蛋白质谱。在过去的 5 年中，有几个研究小组开创了这一研究领域，表明表观遗传学可能在寄生虫基因表达的控制中发挥重要作用。组蛋白修饰是调节基因转录的有效途径，但它们并非单独起作用；相反，它们与其他潜在的表观遗传信息载体（组蛋白变体、小 RNA）和 DNA 序列特异性转录因子协同作用，调节染色质纤维的高级结构，并控制转录机制及时招募到特定基因。关于“组蛋白密码”假说，寄生虫具有丰富的组蛋白修饰酶库，催化位点选择性修饰，随后由识别特定共价标记的效应蛋白进行解释。尽管如此，一些特殊性似乎是刚地弓形虫所特有的。这篇综述综合了目前关于表观遗传学如何有助于控制刚地弓形虫（可能还有其他顶复门生物）基因表达的知识。
