Guzman P, Rivera Chavira B E, Court D L, Gottesman M E, Guarneros G
Centro de Investigación y de Estudios Avanzados del IPN, Mexico D.F., Mexico.
J Bacteriol. 1990 Feb;172(2):1030-4. doi: 10.1128/jb.172.2.1030-1034.1990.
The rap mutation in Escherichia coli prevents the growth of bacteriophage lambda. Phage mutations that overcome rap inhibition (bar) have been mapped to loci in the pL operon. We cloned and sequenced three mutations in two of these loci: barIa to the left arm of the lambda attachment site (attP) and barII in the ssb (ea10) gene. The mutations represent single base-pair changes within nearly identical 16-base-pair DNA segments. Each mutation disrupts a sequence of dyad symmetry within the segment. Plasmids carrying a bar+ sequence downstream to an active promoter are lethal to rap, but not rap+, bacteria. The bar sequences isolated from the lambda bar mutants are not lethal. We synthesized a minimal lambda barIa+ sequence, 5'-TATATTGATATTTATATCATT, and cloned it downstream to an inducible promoter. When transcribed, this sequence is sufficient to kill a rap strain.
大肠杆菌中的rap突变可阻止λ噬菌体生长。克服rap抑制作用的噬菌体突变（bar）已定位到pL操纵子中的位点。我们克隆并测序了其中两个位点的三个突变：barIa位于λ附着位点（attP）的左臂，barII位于ssb（ea10）基因中。这些突变代表几乎相同的16个碱基对DNA片段内的单碱基对变化。每个突变都会破坏该片段内的二重对称序列。携带位于活性启动子下游的bar +序列的质粒对rap细菌具有致死性，但对rap +细菌则无致死性。从λbar突变体中分离出的bar序列没有致死性。我们合成了一个最小的λbarIa +序列，5'-TATATTGATATTTATATCATT，并将其克隆到可诱导启动子的下游。转录时，该序列足以杀死rap菌株。
