A single glycine-rich repeat of Pseudomonas chlororaphis Polyurethanase A mediates secretion of a GST fusion protein in Escherichia coli

Polyurethanase A encoded by pueA from Pseudomonas chlororaphis was shown previously to have a C-terminal secretion signal located downstream of a domain containing three glycine-rich repeats. These glycine-rich repeats are nonapeptide motifs involved in Ca2+-binding found in proteins secreted via type I systems. The role of these repeats in the secretion process is controversial. In the present study, a fusion protein using GST and a single glycine-rich repeat from PueA was analyzed for secretion. Our studies show that secretion of at least one protein, the 27.9 kDa GST protein, can be mediated by a single PueA C-terminal glycine-rich repeat independent of a targeting sequence.