Murray N E, Kelley W S
Mol Gen Genet. 1979 Aug;175(1):77-87. doi: 10.1007/BF00267858.
lambdapolA phages carrying the polA gene in either orientation were isolated and characterised by genetic tests and by assay of the polA gene product after infection of E. coli or induction of lysogens. Lytic infection gave consistently better amplification of DNA polymerase I than that obtained by induction of a lysogen. Optimal amplification of DNA polymerase I was not achieved from the PL promoter of cro-phages, but some advantages accrued when the polA gene was oriented for transcription from the PL promoter of a cro+ phage. lambdapolA phages in which the polA allele was from E. coli strain C600 provided better amplification than phages with the polA allele from E. coli ED8659. Induction of a lambdapolA1 cI857 Qam Sam prophage gave levels of DNA polymerase I approaching 100 times that found in the non-lysogenic Pol+ host. Genetics studies with the lambdapolA phages confirmed the previously postulated orientation of the polA gene within the E. coli genome.
分离出携带polA基因且方向各异的λpolA噬菌体，并通过基因测试以及在感染大肠杆菌或诱导溶原菌后对polA基因产物进行测定来对其进行表征。裂解感染产生的DNA聚合酶I扩增效果始终优于通过诱导溶原菌获得的扩增效果。从cro噬菌体的PL启动子无法实现DNA聚合酶I的最佳扩增，但当polA基因的方向适合从cro⁺噬菌体的PL启动子转录时，会有一些优势。其中polA等位基因来自大肠杆菌菌株C600的λpolA噬菌体比带有来自大肠杆菌ED8659的polA等位基因的噬菌体具有更好的扩增效果。诱导λpolA1 cI857 Qam Sam原噬菌体产生的DNA聚合酶I水平接近非溶原性Pol⁺宿主中发现水平的100倍。对λpolA噬菌体的遗传学研究证实了先前推测的polA基因在大肠杆菌基因组中的方向。
