细菌自然转化的分子机制研究进展

Advances in the molecular mechanism of natural bacterial transformation——A review

自然环境中,具备自然转化能力的细菌可以自发地从外界获取DNA,从而获得新的遗传性状。为能够自然地被转化,细菌需首先建立一个被称作感受态的生理状态并在此状态下表达DNA摄取和加工相关的基因。DNA摄取基因的表达产物可组装一个能将外源DNA摄入细胞质的蛋白复合物。在细胞质中,进入的DNA可同基因组DNA发生同源重组或建立成一个独立的质粒。一般DNA摄入细胞的过程可分为两个阶段,即从外部基质到细胞周质和跨细胞内膜的转运。近年来,包括作者在内的研究人员发现大肠杆菌中存在新的自然质粒转化模式。本文将首先综述近年来细菌自然转化的分子机制,随后简要介绍大肠杆菌中独特的自然质粒转化模式。

Naturally transformable bacteria are able to take up DNA to acquire new genetic traits in the environment. To be naturally transformed, bacteria need to establish a physiological state, called natural competence, in which DNA uptake and processing genes are expressed. DNA uptake proteins assemble a complex to pull exogenous DNA into the cytoplasm where it can recombine with the genome DNA or establish as a plasmid. In general, DNA uptake of bacteria could be divided into two stages： DNA is transported from the milieu to the periplasm at the first stage （for Gram-negative bacteria） and is translocated across the inner membrane at the second stage. Our work and other studies revealed new plasmid DNA transformation modes in Escherichia coll. Here, we first reviewed recent advances in the molecular mechanism of natural transformation and then described the distinctive plasmid transformation mode in E. coll.