Siboo I R, Sieder F, Kumar K, Howe M M, DuBow M S
Department of Microbiology and Immunology, McGill University, Montreal, Canada.
Arch Virol. 2004 Feb;149(2):241-59. doi: 10.1007/s00705-003-0216-4. Epub 2003 Nov 4.
Late during the bacteriophage Mu lytic cycle, Mu DNA must be matured and packaged from its dispersed integration sites in the host DNA in order to produce progeny virions. Whereas control of late gene transcription in Mu is becoming well understood, less is known about the phage morphogenetic process. To investigate the latter, we cloned and sequenced a approximately 4.3-kb region of the phage DNA beginning just upstream of the leftmost late promoter Plys. Previous mapping of amber mutations had located the lysis (lys) and proposed DNA maturation genes D and E in this region. When the DNA sequence was analyzed, seven potential open reading frames were found. DNA sequence analysis of amber mutations in genes D and E identified the sixth and seventh open reading frames as D and E, respectively. Cloning and expression of this region enabled production of cell-free protein extracts that specifically recognize the phage-encoded packaging sequence (pac), a characteristic exhibited by phage maturation enzymes. In addition, the E protein was found to share homology with the large subunit of many phage DNA maturation enzymes. These results support the hypothesis that D and E encode subunits of the Mu DNA maturation enzyme.
在噬菌体Mu裂解周期的后期，Mu DNA必须从其在宿主DNA中的分散整合位点成熟并包装，以便产生子代病毒粒子。虽然对Mu中晚期基因转录的控制已逐渐为人所知，但对噬菌体形态发生过程的了解却较少。为了研究后者，我们克隆并测序了噬菌体DNA约4.3 kb的区域，该区域始于最左侧晚期启动子Plys的上游。先前对琥珀突变的定位已将裂解（lys）以及推测的DNA成熟基因D和E定位在该区域。对DNA序列进行分析时，发现了七个潜在的开放阅读框。对基因D和E中的琥珀突变进行DNA序列分析，分别将第六和第七个开放阅读框鉴定为D和E。该区域的克隆和表达使得能够产生特异性识别噬菌体编码包装序列（pac）的无细胞蛋白质提取物，这是噬菌体成熟酶所具有的特征。此外，发现E蛋白与许多噬菌体DNA成熟酶的大亚基具有同源性。这些结果支持了D和E编码Mu DNA成熟酶亚基的假说。
