Zambetti G P, Shuster R C
Mol Gen Genet. 1984;193(2):322-6. doi: 10.1007/BF00330688.
The activity of the lambda P gene product at various multiplicities of infection (m.o.i.) was examined in CI- conditions using an assay which measures the disappearance of the rapidly-sedimenting closed-circular (c.c.) form of phage DNA. When cells were infected with lambda CI857 at multiplicities of 5 phage/cell or less, between 65%-75% c.c. DNA was lost during incubation. If the multiplicity of infection was increased to 10 phage/cell or greater, a marked inhibition in the cleavage of c.c. DNA was observed. When bacteria were infected with either lambda CI857CII2002 or lambda CI857cro27 at low m.o.i., the usual 65%-75% decrease in the percentage of c.c. phage DNA occurred during incubation. In contrast, no losses in c.c. DNA were noted after infection with lambda CI857cro27susP3. At high m.o.i., the cleavage of c.c. DNA was inhibited after infection with lambda CI857CII2002, but not after infection with lambda CI857cro27. It is concluded that at high m.o.i. in CI- infections, the expression of gene P is unaffected by the CII gene product, but is inhibited by the increased intracellular levels of cro protein.
使用一种可测量噬菌体DNA快速沉降的闭环（c.c.）形式消失情况的检测方法，在CI-条件下，于不同感染复数（m.o.i.）下检测了λ P基因产物的活性。当细胞以5个噬菌体/细胞或更低的感染复数用λ CI857感染时，在孵育过程中65%-75%的c.c. DNA会丢失。如果感染复数增加到10个噬菌体/细胞或更高，则会观察到c.c. DNA切割受到明显抑制。当细菌以低m.o.i.用λ CI857CII2002或λ CI857cro27感染时，在孵育过程中c.c.噬菌体DNA的百分比通常会下降65%-75%。相比之下，用λ CI857cro27susP3感染后，未观察到c.c. DNA的损失。在高m.o.i.时，用λ CI857CII2002感染后c.c. DNA的切割受到抑制，但用λ CI857cro27感染后则未受抑制。得出的结论是，在CI-感染的高m.o.i.情况下，基因P的表达不受CII基因产物的影响，但会受到cro蛋白细胞内水平升高的抑制。
