Genetic Control of the Transport of Hexose Phosphates in Escherichia coli: Mapping of the uhp Locus.

A number of mutations affecting the transport of hexose phosphates in Escherichia coli were ordered within the uhp locus. Three-point crosses by transduction or conjugation allowed the ordering of the alleles relative to the adjacent pyrE marker. The same linear map was obtained by both methods. This, combined with the regulatory properties of revertants of these mutants, allowed a tentative identification of two genes, one presumably coding for the transport system (uhpT) and the other(s) specifying a regulatory element (uhpR). The order of these is pyrE-uhpT-uhpR. Mutants exhibiting constitutive expression of the transport system were isolated. This behavior is genetically linked to the uhp locus, but more precise localization was not possible.