Lewis J A, Hatfull G F
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
Mol Microbiol. 2000 Jan;35(2):350-60. doi: 10.1046/j.1365-2958.2000.01695.x.
The well-characterized mycobacteriophage L5 forms stable lysogens in Mycobacterium smegmatis. Establishment of lysogeny involves integration of the phage genome into the chromosome of its mycobacterial hosts through an integrase-mediated site-specific recombination event. As L5 lysogens spontaneously generate free phage particles, prophage excision must also occur, although an L5 excisionase gene had not been identified. We show here that L5 gene 36 encodes the phage excisionase and is a small, heat-stable 56-amino-acid protein that strongly stimulates excisive recombination both in vivo and in vitro. The ability to manipulate the highly directional phage integration and excision reactions will provide powerful tools for the introduction, curing and recovery of foreign genes in recombinant mycobacterial strains.
特征明确的分枝杆菌噬菌体L5可在耻垢分枝杆菌中形成稳定的溶原菌。溶原性的建立涉及噬菌体基因组通过整合酶介导的位点特异性重组事件整合到其分枝杆菌宿主的染色体中。由于L5溶原菌会自发产生游离噬菌体颗粒，因此原噬菌体切除也必然会发生，尽管尚未鉴定出L5切除酶基因。我们在此表明，L5基因36编码噬菌体切除酶，它是一种小的、热稳定的56个氨基酸的蛋白质，在体内和体外均能强烈刺激切除重组。操纵高度定向的噬菌体整合和切除反应的能力将为在重组分枝杆菌菌株中导入、清除和回收外源基因提供强大的工具。
