Boyce J D, Davidson B E, Hillier A J
Russell Grimwade School of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia.
Appl Environ Microbiol. 1995 Nov;61(11):4099-104. doi: 10.1128/aem.61.11.4099-4104.1995.
Bacteriophage BK5-T is a small isometric-headed temperate phage that infects Lactococcus lactis subsp. cremoris. Northern (RNA) analysis of mRNA produced by lysogenic strains containing BK5-T prophage revealed four major BK5-T transcripts that are 0.8, 1.3, 1.8, and 1.8 kb in size and enabled a transcription map of the prophage genome to be prepared. The position and size of each transcript corresponded closely to the position and size of open reading frames predicted from the nucleotide sequence of BK5-T. Analysis of the transcripts suggested that one of them was derived from the gene encoding the BK5-T integrase and another was from the gene encoding the BK5-T homolog of the lambda cI repressor. Computer analysis of the nucleotide sequence upstream of the BK5-T cI homolog predicted the presence of a pair of divergent promoters and three inverted repeat sequences, features characteristic of temperature-phage immunity regions. By analogy with lambda, the three inverted repeat sequences could be binding sites for cI or Cro homologs and the two divergent promoters could initiate transcription through the BK5-T equivalents of cI and cro.
噬菌体BK5-T是一种头部呈小型等面体的温和噬菌体，可感染乳酸乳球菌乳脂亚种。对含有BK5-T原噬菌体的溶原性菌株产生的mRNA进行的Northern（RNA）分析揭示了四种主要的BK5-T转录本，其大小分别为0.8、1.3、1.8和1.8 kb，并据此绘制了原噬菌体基因组的转录图谱。每个转录本的位置和大小与根据BK5-T核苷酸序列预测的开放阅读框的位置和大小密切对应。对这些转录本的分析表明，其中一个转录本来自由编码BK5-T整合酶的基因，另一个来自编码BK5-T λ cI阻遏物同源物的基因。对BK5-T cI同源物上游核苷酸序列的计算机分析预测存在一对反向启动子和三个反向重复序列，这些是温敏噬菌体免疫区域的特征。与λ噬菌体类似，这三个反向重复序列可能是cI或Cro同源物的结合位点，而两个反向启动子可通过BK5-T中与cI和cro等效的基因启动转录。
