The genus Habenivirus which includes Ralstonia virus ϕRSM encodes a site-specific integrase of a small serine recombinase belonging to the resolvase/invertase family. Here we describe the integrative/excisive recombination reactions mediated by ϕRSM integrase using in vitro assays. The products of attP/attB recombination, i.e. attL and attR, were exactly identical to those found in the prophage ϕRSM in R. solanacearum strains. The minimum size of attB required for integration was determined to be 37 bp, containing a 13 bp core and flanking sequences of 4 bp on the left and 20 bp on the right. ϕRSM integrative recombination proceeds efficiently in vitro in the absence of additional proteins or high-energy cofactors. Excision of a functional phage genome from a prophage fragment was demonstrated in vitro, demonstrating two-way activity of ϕRSM1 integrase. This is the first example of a small serine recombinase from the resolvase/invertase group that functions in integrative and excisive recombination for filamentous phages. This serine integrase could be used as a tool for several genome engineering applications.

属Habenivirus包括青枯病毒φRSM编码小丝氨酸的位点特异性重组酶整合属于该解离/转化的家庭。在这里，我们描述了使用体外测定方法由ϕRSM整合酶介导的整合/决定性重组反应。attP / attB重组的产物，即attL和attR，与青枯菌菌株Prohage ϕRSM中发现的产物完全相同。确定整合所需的attB的最小大小为37 bp，包含13 bp的核心，左侧为4 bp，右侧为20 bp的侧翼序列。在没有其他蛋白质或高能辅助因子的条件下，RSM整合重组可在体外高效进行。在体外证明了从噬菌体片段中切除功能性噬菌体基因组，证明了ϕRSM1整合酶的双向活性。这是来自resolvase / invertase组的小丝氨酸重组酶的第一个实例，该酶在丝状噬菌体的整合和兴奋性重组中起作用。该丝氨酸整合酶可以用作几种基因组工程应用的工具。