CONSTRUCTION AND IN-VIVO ANALYSIS OF NEW SPLIT LACTOSE PERMEASES

The capacity of incomplete segments of Escherichia coli lactose permea se to form transport-competent complexes in vivo was further tested. T wo series of mutant lacY genes were constructed. One encoded N-termina l lactose permease segments of different length. The proteins specifie d by the other group contained deletions of different length and locat ion within the N-terminal region. Several pairs of such mutant protein s reconstituted active lactose transport. For certain combinations dup lications of protein segments were compatible with the formation of an active carrier. Duplication of helices could also be tolerated, when part of a single polypeptide chain.