Construction and in vivo analysis of new split lactose permeases.

The capacity of incomplete segments of Escherichia coli lactose permease to form transport-competent complexes in vivo was further tested. Two series of mutant lacY genes were constructed. One encoded N-terminal lactose permease segments of different length.

Reconstitution of an active lactose carrier in vivo by simultaneous synthesis of two complementary protein fragments.

Escherichia coli lactose permease mediates the proton-driven translocation of galactosides across the cytoplasmic membrane. To define regions important for membrane insertion as well as for biological function, we constructed plasmids encoding different portions of the lactose carrier. Among several lacY deletions, two were obtained that encoded mutant proteins with complementary amino acid sequences.