α complementation in the Cre recombinase enzyme

The Cre-IoxP system is increasingly exploited for spatial and temporal gene inactivation. Here we present a novel approach to achieve this goal of selective gene inactivation. Following the model of complementation in the beta-galactosidase enzyme, where the enzyme is split into independent polypeptides which are able to associate and maintain the enzymatic activity, we divided the Cre recombinase into two independent polypeptides (one containing the NH2 terminus (alpha) and a second one containing the COOH-terminus (beta)). Individually, the two polypeptides have no detectable activity. However, when coexpressed the polypeptides are able to associate, giving rise to Cre enzymatic activity, which optimally is as high as 30% of that seen with wildtype Cre recombinase in vitro. We present this strategy as a modification of the traditional Cre-IoxP system, which could be used to obtain a highly specific recombination pattern by expressing the two halves under the control of separate promoters. (C) 2003 Wiley-Liss, Inc.