Compartmentalization of the proteins encoded by IS50R

IS50R is a transposable genetic element that serves as the right inverted repeat of the transposon Tn5. Earlier work has shown that IS50R encodes at least two proteins (called P1 and P2) involved in transposition. In this paper, we describe the localization properties of the proteins encoded on this repeat. Strains were constructed that overproduced either these two proteins or hybrids between beta-galactosidase and the IS50R proteins. An antiserum was raised against the hybrid proteins, and this was used to study the localization of P1 and P2. Based on studies in maxicells as well as in growing cells, we show that P1 and P2 are localized differently in the cell. P2 is a cytoplasmic protein, while P1 largely fractionates with the membrane.