Kreuzer K N, McEntee K, Geballe A P, Cozzarelli N R
Mol Gen Genet. 1978 Nov 29;167(2):129-37. doi: 10.1007/BF00266906.
Defective lambda transducing phages for the nalA region of the Escherichia coli chromosome were isolated from a lysogen in which lambda is inserted in the nearby glpT gene. The three classes of transducing phages designated lambdanrdA, lambdaubiG, and lambdadnalA contained bacterial DNA extending from glpT through nrdA, ubiG, and nalA, respectively. The bacterial genes are in the left arm of the lambda chromosome. Of the eleven polypeptides coded by lambdadnalA that were resolved by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate only one was not also specified by lambdadubiG. This 105,000 dalton polypeptide is the nalA gene product. The electorphoretic mobility and isoelectric point of this protein were unaffected by a nalA mutation (nalA48) that confers nalidixic acid resistance. Temperature-sensitive and amber mutations in the nalA gene were isolated using a lambdadnalA48 lysogen which is heterodiploid for nalA. The conditional lethality of these mutations proves that nalA is an essential locus.
从一个λ噬菌体插入附近glpT基因的溶原菌中分离出大肠杆菌染色体nalA区域有缺陷的λ转导噬菌体。三类转导噬菌体分别命名为λnrdA、λubiG和λdnalA，它们所含的细菌DNA分别从glpT延伸至nrdA、ubiG和nalA。这些细菌基因位于λ染色体的左臂。在十二烷基硫酸钠存在下通过聚丙烯酰胺凝胶电泳解析出的由λdnalA编码的11种多肽中，只有一种不是由λdubiG编码的。这种105,000道尔顿的多肽是nalA基因产物。该蛋白质的电泳迁移率和等电点不受赋予萘啶酸抗性的nalA突变（nalA48）的影响。利用对nalA为异二倍体的λdnalA48溶原菌分离出nalA基因的温度敏感型和琥珀型突变。这些突变的条件致死性证明nalA是一个必需基因座。
