Ontell M P, Nakada D
J Virol. 1980 May;34(2):438-45. doi: 10.1128/JVI.34.2.438-445.1980.
Infection of Escherichia coli with T7 gene 2 mutant phage was abortive; concatemeric phage DNA was synthesized but was not packaged into the phage head, resulting in an accumulation of DNA species shorter in size than the phage genome, concomitant with an accumulation of phage head-related structures. Appearance of concatemeric T7 DNA in gene 2 mutant phage infection during onset of T7 DNA replication indicates that the product of gene 2 was required for proper processing or packaging of concatemer DNA rather than for the synthesis of T7 progeny DNA or concatemer formation. This abortive infection by gene 2 mutant phage could be rescued by rifampin. If rifampin was added at the onset of T7 DNA replication, concatemeric DNA molecules were properly packaged into phage heads, as evidenced by the production of infectious progeny phage. Since the gene 2 product acts as a specific inhibitor of E. coli RNA polymerase by preventing the enzyme from binding T7 DNA, uninhibited E. coli RNA polymerase in gene 2 mutant phage-infected cells interacts with concatemeric T7 DNA and perturbs proper DNA processing unless another inhibitor of the enzyme (rifampin) was added. Therefore, the involvement of gene 2 protein in T7 DNA processing may be due to its single function as the specific inhibitor of the host E. coli RNA polymerase.
用T7基因2突变噬菌体感染大肠杆菌是流产性的；串联噬菌体DNA被合成，但未被包装到噬菌体头部，导致比噬菌体基因组短的DNA种类积累，同时伴有噬菌体头部相关结构的积累。在T7 DNA复制开始时，串联T7 DNA在基因2突变噬菌体感染中出现，这表明基因2的产物是串联DNA正确加工或包装所必需的，而不是T7子代DNA合成或串联体形成所必需的。基因2突变噬菌体的这种流产性感染可用利福平挽救。如果在T7 DNA复制开始时加入利福平，串联DNA分子会被正确包装到噬菌体头部，这可从感染性子代噬菌体的产生得到证明。由于基因2产物通过阻止大肠杆菌RNA聚合酶结合T7 DNA而作为该酶的特异性抑制剂，在基因2突变噬菌体感染的细胞中，未受抑制的大肠杆菌RNA聚合酶与串联T7 DNA相互作用并扰乱DNA的正确加工，除非加入该酶的另一种抑制剂（利福平）。因此，基因2蛋白参与T7 DNA加工可能是由于其作为宿主大肠杆菌RNA聚合酶特异性抑制剂的单一功能。
