Sánchez C, Hernández de Rojas A, Martínez B, Argüelles M E, Suárez J E, Rodríguez A, Mayo B
Instituto de Productos Lácteos de Asturias (CSIC), Carretera de Infiesto s/n, Villaviciosa, Asturias, 33300-, Spain.
Plasmid. 2000 Nov;44(3):239-49. doi: 10.1006/plas.2000.1482.
The complete sequence of the 10.9-kbp bacteriocinogenic plasmid pBL1 from Lactococcus lactis subsp. lactis IPLA 972 has been determined. Thirteen ORFs were encountered, of which 5 were incomplete. pBL1 proved to be a narrow-host-range plasmid which replicates neither in Bacilus subtilis nor in Lactobacillus spp. The structural organization of the pBL1 replication region was highly similar to other well-known theta-replicating plasmids of lactococci, at both the untranslated (the replication origin) and the translated (repB and orfX) sequences. As in other plasmids, the product of orfX was not necessary for plasmid replication. However, it was shown to be involved in plasmid stability. Three genes organized in an operon-like structure encompassed, most likely, the bacteriocin-encoding region. Upstream of the origin of replication a nicking site (oriT) was found. This oriT sequence proved to be functional by mobilization of plasmids wearing it. One complete and several partial IS elements were identified on pBL1.
已测定乳酸乳球菌乳酸亚种IPLA 972的10.9-kbp产细菌素质粒pBL1的完整序列。共发现13个开放阅读框（ORF），其中5个不完整。事实证明，pBL1是一种窄宿主范围质粒，它既不在枯草芽孢杆菌中复制，也不在乳杆菌属中复制。pBL1复制区域的结构组织在未翻译序列（复制起点）和翻译序列（repB和orfX）方面与其他著名的乳球菌θ复制质粒高度相似。与其他质粒一样，orfX的产物对质粒复制并非必需。然而，已证明它与质粒稳定性有关。以操纵子样结构组织的三个基因很可能包含细菌素编码区域。在复制起点上游发现了一个切口位点（oriT）。通过携带该oriT序列的质粒的转移，证明该oriT序列具有功能。在pBL1上鉴定出一个完整的和几个部分的插入序列（IS）元件。
