Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
Biochim Biophys Acta Gene Regul Mech. 2019 Jul;1862(7):752-758. doi: 10.1016/j.bbagrm.2018.01.003. Epub 2018 Jan 31.
Cell-to-cell differences in bacterial gene expression can merely reflect the occurrence of noise. In certain cases, however, heterogeneous gene expression is a programmed event that results in bistable expression. If bistability is heritable, bacterial lineages are formed. When programmed bistability is reversible, the phenomenon is known as phase variation. In certain cases, bistability is controlled by genetic mechanisms (e. g., DNA rearrangement). In other cases, bistability has epigenetic origin. A robust epigenetic mechanism for the formation of bacterial lineages is the formation of heritable DNA methylation patterns. However, bistability can also arise upon propagation of gene expression patterns by feedback loops that are stable upon cell division. This review describes examples of bistability and phase variation in Salmonella enterica and discusses their adaptive value, sometimes in a speculative manner.
细菌基因表达的细胞间差异可能仅仅反映了噪声的发生。然而，在某些情况下，异质基因表达是一个程序化的事件，导致双稳态表达。如果双稳态是可遗传的，那么细菌谱系就会形成。当程序化的双稳态是可逆的时，这种现象被称为相位变化。在某些情况下，双稳态受遗传机制的控制（例如，DNA 重排）。在其他情况下，双稳态具有表观遗传的起源。细菌谱系形成的稳健表观遗传机制是可遗传的 DNA 甲基化模式的形成。然而，双稳态也可以通过在细胞分裂时稳定的反馈环来传播基因表达模式而产生。本综述描述了沙门氏菌中双稳态和相位变化的例子，并以推测的方式讨论了它们的适应价值。
