The penicillin-binding protein 2 genes (pen4) of penicillin-resistant Neisseria meningitidis have a mosaic
structure that has arisen by the introduction of regions from the penA genes of Neisseria flavescens or Neisseria
cinerea. Chromosomal DNA from both N. cinerea and N.favescens could transform a penicillin-susceptible isolate
of N. meningitidis to increased resistance to penicillin. With N. flavescens DNA, transformation to resistance was
accompanied by the introduction of the N. flavescens penA gene, providing a laboratory demonstration of the
interspecies recombinational events that we believe underlie the development of penicillin resistance in many
meningococci in nature. Surprisingly, with N. cinerea DNA, the penicillin-resistant transformants did not obtain
the N. cinerea penA gene. However, the region of the penA gene derived from N. cinerea in N. meningitidis K196
contained an extra codon (Asp-345A) which was not found in any of the four N. cinerea isolates that we examined
and which is known to result in a decrease in the affinity of PBP 2 in gonococci.