Galán J E, Nakayama K, Curtiss R
Department of Biology, Washington University, Saint Louis, MO 63130.
Gene. 1990 Sep 28;94(1):29-35. doi: 10.1016/0378-1119(90)90464-3.
The asd mutants of Salmonella typhimurium have an obligate requirement for diaminopimelic acid (DAP) and will undergo lysis in environments deprived of DAP. This has allowed the development of a balanced-lethal system for the expression of heterologous antigens in vaccine strains using vectors containing the wild-type asd gene from Streptococcus mutans and asd mutant Salmonella hosts [Nakayama et al., Biotechnology 6 (1988) 693-697]. We have cloned the asd gene from S. typhimurium, characterized the gene product and used this gene to construct Asd+ expression cloning vectors. In addition we have constructed an asd cassette and a transposon derived from Tn5 that allow the rapid modification of other vectors for use with delta asd vaccine strains of S. typhimurium adding versatility to the Asd+ vector/delta asd host system of plasmid maintenance.
鼠伤寒沙门氏菌的 asd 突变体对二氨基庚二酸（DAP）有绝对需求，并且在缺乏 DAP 的环境中会发生裂解。这使得利用含有变形链球菌野生型 asd 基因的载体和 asd 突变沙门氏菌宿主，在疫苗菌株中表达异源抗原的平衡致死系统得以发展[中山等人，《生物技术》6（1988）693 - 697]。我们已经从鼠伤寒沙门氏菌中克隆了 asd 基因，对基因产物进行了表征，并使用该基因构建了 Asd⁺表达克隆载体。此外，我们构建了一个 asd 盒式结构和一个源自 Tn5 的转座子，它们能够快速修饰其他载体，以便与鼠伤寒沙门氏菌的Δasd 疫苗菌株一起使用，从而增加了 Asd⁺载体/Δasd 宿主质粒维持系统的通用性。
