Pouwels P H, Leer R J
Department Molecular Genetics and Gene-Technology, TNO Medical Biological Laboratory, Rijswijk, The Netherlands.
Antonie Van Leeuwenhoek. 1993;64(2):85-107. doi: 10.1007/BF00873020.
This paper reviews the present knowledge of the structure and properties of small (< 5 kb) plasmids present in Lactobacillus spp. The data show that plasmids from Lactobacillus spp., like many plasmids from other Gram-positive bacteria, display a modular organization and replicate by a mechanism of rolling circle replication. Structurally, plasmids from lactobacilli are closely related to plasmids from other Gram-positive bacteria. They contain elements (plus- and minus origin of replication, element(s) for control of plasmid replication, mobilization function) showing extensive similarity to analogous elements in plasmids from these other organisms. It is believed that lactobacilli have acquired such elements by intra- and/or intergenic transfer mechanisms. The first part of the review is concluded with a description of plasmid vectors with a Lactobacillus replicon and integrative vectors, including data concerning their structural and segregational stability. In the second part of this review we describe the progress that has been made during the last few years in identifying and characterizing elements that control expression of genetic information in lactobacilli. Based on the sequence of eleven identified and twenty presumed promoters, some preliminary conclusions can be drawn regarding the structure of Lactobacillus promoters. A typical Lactobacillus promoter shows significant similarity to promoters from E. coli and B. subtilis. An analysis of published sequences of seventy genes indicates that the region encompassing the translation start codon AUG also shows extensive similarity to that of E. coli and B. subtilis. Codon usage of Lactobacillus genes is not random and shows interspecies as well as intraspecies heterogeneity. Interspecies differences may, in part, be explained by differences in G+C content of different lactobacilli. Differences in gene expression levels can, to a large extent, account for intraspecies differences of codon usage bias. Finally, we review the knowledge that has become available concerning protein secretion and heterologous gene expression in lactobacilli. This part is concluded with a compilation of data on the expression in Lactobacillus of heterologous genes under the control of their own promoter or under control of a Lactobacillus promoter.
本文综述了目前对乳酸杆菌属中存在的小（<5 kb）质粒的结构和特性的认识。数据表明，乳酸杆菌属的质粒与其他革兰氏阳性菌的许多质粒一样，呈现模块化组织，并通过滚环复制机制进行复制。在结构上，乳酸杆菌的质粒与其他革兰氏阳性菌的质粒密切相关。它们包含的元件（正向和反向复制起点、控制质粒复制的元件、移动功能元件）与这些其他生物的质粒中的类似元件具有广泛的相似性。据信，乳酸杆菌是通过基因内和/或基因间转移机制获得这些元件的。综述的第一部分以对具有乳酸杆菌复制子的质粒载体和整合载体的描述结束，包括有关其结构和分离稳定性的数据。在本综述的第二部分中，我们描述了过去几年在鉴定和表征控制乳酸杆菌遗传信息表达的元件方面所取得的进展。基于11个已鉴定和20个推测的启动子的序列，可以就乳酸杆菌启动子的结构得出一些初步结论。典型的乳酸杆菌启动子与大肠杆菌和枯草芽孢杆菌的启动子具有显著的相似性。对70个基因的已发表序列分析表明，包含翻译起始密码子AUG的区域也与大肠杆菌和枯草芽孢杆菌的该区域具有广泛的相似性。乳酸杆菌基因的密码子使用并非随机，并且表现出种间以及种内的异质性。种间差异部分可以由不同乳酸杆菌的G+C含量差异来解释。基因表达水平的差异在很大程度上可以解释种内密码子使用偏好的差异。最后，我们综述了有关乳酸杆菌中蛋白质分泌和异源基因表达的现有知识。这部分以关于在其自身启动子或乳酸杆菌启动子控制下异源基因在乳酸杆菌中的表达数据汇编结束。
