A stable shuttle vector system for efficient genetic complementation of Helicobacter pylori strains by transformation and conjugation

作者：Heuermann D; Haas R^*

来源：Molecular and General Genetics, 1998, 257(5): 519-528.

• plasmid vector
• bacterial conjugation
• natural transformation competence
• green fluorescent protein
• homologous recombination

A versatile plasmid shuttle vector system was constructed, which is useful for genetic complementation of Helicobacter pylori strains or mutants with cloned genes of homologous or heterologous origin. The individual plasmid vectors consist of the minimal essential genetic elements, including an origin of replication for Escherichia coli, a H. pylori-specific replicon originally identified on a small cryptic H. pylori plasmid, an oriT sequence and a multiple cloning site. Shuttle plasmid pHe12 carries a chloramphenicol resistance cassette (cat(GC)) and pHe13 contains a kanamycin resistance gene (aphA-3) as the selectable marker; both are functional in E. coli and H. pylori. The shuttle plasmids were introduced into the H. pylori strain P1 by natural transformation. A efficiency of 7.0 x 10(-7) and 4.7 x 10(-7) transformants per viable recipient was achieved with pHe12 and pHe13, respectively, and both vectors showed stable, autonomous replication in N. pylori. An approximately 100-fold higher H. pylori transformation rate was obtained when the shuttle vectors for transformation were isolated from the homologous H. pylori strain, rather than E. coli, indicating that DNA restriction and modification mechanisms play a crucial role in plasmid transformation. Interestingly, both shuttle vectors could also be mobilized efficiently from E. coli into different H. pylori recipients, with pHe12 showing an efficiency of 2.0 x 10(-5) transconjugants per viable H. pylori P1 recipient. Thus, DNA restriction seems to be strongly reduced or absent during conjugal transfer. The functional complementation of a lecA-deficient H. pylori mutant by the cloned H. pylori recA' gene, and the expression of the heterologous green fluorescent protein (GFP) in H. pylori demonstrate the general usefulness of this system, which will significantly facilitate the molecular analysis of H. pylori virulence factors in the future.

• 出版日期1998-3