Springer B, Sander P, Sedlacek L, Ellrott K, Böttger E C
Institut für Medizinische Mikrobiologie, Medizinische Hochschule Hannover, Germany.
Int J Med Microbiol. 2001 Mar;290(8):669-75. doi: 10.1016/S1438-4221(01)80004-7.
Integrative vectors expressing foreign genes are used as tools for the development of recombinant vaccines in mycobacteria since it is assumed that these vectors are stably maintained even without antibiotic selection. We here demonstrate that integration-proficient vectors are lost from the mycobacterial genome in high frequency. Loss of integrated vectors occurred in recA+ and in recA-strains, indicating a RecA-independent mechanism. Loss of the integrated vector was prevented when integrase gene function was carried on a separate plasmid that is unable to replicate in mycobacteria, indicating that excision is a function of integrase. By providing attP in cis and integrase function in trans, vectors integrating at the attB site are stably maintained, even when carrying genes that deleteriously affect the host.
表达外源基因的整合载体被用作分枝杆菌重组疫苗开发的工具，因为据推测这些载体即使在没有抗生素选择的情况下也能稳定维持。我们在此证明整合能力强的载体在分枝杆菌基因组中高频丢失。整合载体的丢失在recA+菌株和recA-菌株中均会发生，表明这是一种不依赖RecA的机制。当整合酶基因功能由一个无法在分枝杆菌中复制的单独质粒携带时，整合载体的丢失得以防止，这表明切除是整合酶的一种功能。通过顺式提供attP和反式提供整合酶功能，即使携带对宿主有有害影响的基因，在attB位点整合的载体也能稳定维持。
