细菌自然转化的分子机制及生物学功能研究进展

Molecular mechanisms and biological functions of bacteria natural transformation

摘要:

基因的水平转移在细菌的进化中起着非常重要的作用。自然界中的细菌之间主要通过3种机制进行基因水平转移：由噬菌体介导的转导、接合转移和自然转化。自然转化是指自然感受态的细菌能够自发地从外界环境中摄取DNA分子并整合到自身基因组上的过程。该现象首先发现于肺炎链球菌，目前至少有83种细菌被发现具有发生自然转化的能力，其中革兰氏阳性菌以肺炎链球菌(Streptococcus pneumoniae，S. pneumoniae)为代表，革兰氏阴性菌以奈瑟氏菌(Neisseria)为代表，对其自然转化机制的研究和认识较为清楚，但不同细菌之间自然转化的机制有所差异。自然转化的生物学功能一直以来有以下几种推测：获取营养、修复DNA损伤、生物进化，而近年来对此认识争论不休。本文将详细描述细菌自然转化的分子机制，并对其主要的生物学功能争论焦点进行评述，以期对细菌自然转化有更深入的理解和认识。

关键词:自然转化，DNA转运，感受态，生物学功能

Abstract:

Horizontal gene transfer (HGT) plays an important role in the evolution of bacteria. HGT occurs mainly through three mechanisms: transduction which is mediated by bacterial phage, conjugation and natural transformation. Natural transformation is the process by which natural competent bacteria can take up DNA from the environment and integrate it into their own genomes. Natural transformation was first found in Streptococcus pneumoniae in 1928. Until now, at least 83 bacterial species have been found to be natural competent. Among them, the natural transformation mechanism of Gram-positive bacteria Streptococcus pneumoniae and Gram-negative bacteria Neisseria were studied well, respectively. The biological functions of natural transformation have been hypothesized as follows: obtaining nutrition, repairing DNA damage, and biological evolution. However, there are still debates on this. In this paper, it will describe the molecular mechanism of bacterial natural transformation in details, and discuss the biological function of natural transformation. It will be helpful to further understand the bacterial natural transformation.

Key words:Natural transformation, DNA transfer, Competence, Biological function