[Inversion of the metE-oriC-rpsE chromosome segment in Escherichia coli K12].

We have described recently a large inversion of the Escherichia coli chromosome (designated udpPf1), including region of the chromosomal replication region (oriC). The udpPf1 inversion was induced by Tn10 transposon (metE::Tn10). It results in increased expression of the uridine phosphorylase gene (udp) which is closely linked to the metE gene. The data of conjugational and transductional experiments presented in this report demonstrate that the udpPf1 inversion covers a chromosomal segment extending over 12 min of the E. coli genetic map and including the rpsE, crp and metE::Tn5 markers. The results are presented indicating that the increased uridine phosphorylase activity is due to fusion of the udp gene to a more strong promoter located, probably, in the operon for ribosomal proteins cluster, near 73 min on the E. coli chromosome.