Chandry P Scott, Moore Sean C, Davidson Barrie E, Hillier Alan J
Food Science Australia, Werribee, Victoria, Australia.
FEMS Microbiol Lett. 2002 Oct 29;216(1):85-90. doi: 10.1111/j.1574-6968.2002.tb11419.x.
Lactococcus lactis bacteriophage sk1 can transduce plasmids containing the phage cos site and surrounding DNA sequences at frequencies as high as 2x10(-3) transductants per PFU. Deletion analysis demonstrated that the presence of phage DNA spanning cos and putative R sites were the most important for efficient plasmid transduction. Inserts of 440 bp containing cos and the R sites were sufficient to induce transduction frequencies of 10(-4) transductants per PFU. The role of the R1 site was investigated by altering 14 of the 19 bases in the site. This resulted in a two-fold decrease in transduction frequency compared to a 26-fold decrease in transduction following deletion of the entire site. It was demonstrated that transducing plasmids were packaged as linear trimeric concatemers commencing at the cos site.
乳酸乳球菌噬菌体sk1能够以高达每噬菌斑形成单位（PFU）2×10⁻³个转导子的频率转导含有噬菌体粘性末端位点（cos位点）及周围DNA序列的质粒。缺失分析表明，跨越cos位点和假定R位点的噬菌体DNA的存在对于高效的质粒转导最为重要。包含cos位点和R位点的440 bp插入片段足以诱导每PFU产生10⁻⁴个转导子的转导频率。通过改变该位点19个碱基中的14个来研究R1位点的作用。与整个位点缺失后转导频率下降26倍相比，这导致转导频率下降了两倍。结果表明，转导质粒是以从cos位点开始的线性三聚体串联体形式进行包装的。
