Mycoplasma Species

Unsurprisingly, the first attempt was in the sequenced bacterial pathogens with the smallest genomic contents, Mycoplasma genitalium and M. pneumoniae [26]. The scope of this study was to define the genes that cannot be mutated and are therefore essential for cellular life. In brief, pools of mutants obtained after elec-troporation of a plasmid containing the composite transposon Tn4002 from S. aureus were propagated in culture under selective pressure and genomic DNA was isolated. A laborious method was used to identify the junctions between the transposons and the chromosome. The transposon insertion sites, amplified by inverse PCR using primers specific for the transposon, were cloned and the recombinant plasmids were subsequently sequenced. The sequencing of 2209 clones defined 685 and 669 distinct insertion sites that occurred in 140 and 179 different genes of M. genitalium and M. pneumoniae, respectively. Unfortunately, in this study, the transposon mutants were analyzed within mixed populations, thus leaving no resource that could be subsequently used for functional studies. In contrast, arrayed libraries of defined transposon mutants have been constructed more recently for several pathogens.

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