Chao Liu, Qiyu Bao, Fuping Song, Ming Sun, Dafang Huang, Guiming Liu, Ziniu Yu
State Key Laboratory of Agricultural Microbiology and National Engineering Research Center of Microbe Pesticides, Huazhong Agricultural University, Wuhan 430070, China.
Plasmid. 2007 Jan;57(1):44-54. doi: 10.1016/j.plasmid.2006.06.002. Epub 2006 Aug 9.
The complete nucleotide sequence of a large (67kb) cryptic plasmid pBMB67 from Bacillus thuringiensis strain YBT-1520 was determined. Of the 74 predicted open reading frames (ORFs), 25 (34%) were assigned putative functions, 18 (24%) encoded conserved hypothetical proteins, and 31 (42%) had no homology to any genes present in the current open databases. The ORFs with similar functions were organized in a modular structure; thus, the DNA sequence of pBMB67 could be functionally divided into three modules, including a 39kb transfer region encoding homologs of the Agrobacterium tumefaciens VirB/D4 system components VirB1, VirB4, VirB11, and VirD4, as well as homologs of Gram-positive conjugation proteins. We also found a potential operon that was analogous to the Rap-Phr cassettes from Bacillus subtilis, which are involved in cell-cell communication and transcriptional regulation. Thus, we suggest that pBMB67 is likely to be implicated in cell-cell signaling and plays a role in the regulation of several cellular processes, with the production of exoprotease being one of the candidates.
测定了苏云金芽孢杆菌YBT - 1520菌株中一个大的（67kb）隐蔽质粒pBMB67的完整核苷酸序列。在74个预测的开放阅读框（ORF）中，25个（34%）被赋予了假定功能，18个（24%）编码保守的假定蛋白，31个（42%）与当前开放数据库中存在的任何基因均无同源性。具有相似功能的ORF以模块化结构组织；因此，pBMB67的DNA序列在功能上可分为三个模块，包括一个39kb的转移区域，该区域编码根癌土壤杆菌VirB/D4系统组分VirB1、VirB4、VirB11和VirD4的同源物，以及革兰氏阳性接合蛋白的同源物。我们还发现了一个潜在的操纵子，它类似于枯草芽孢杆菌的Rap - Phr盒，参与细胞间通讯和转录调控。因此，我们认为pBMB67可能参与细胞间信号传导，并在几个细胞过程的调控中发挥作用，胞外蛋白酶的产生就是其中一个候选过程。
