Figure 6
A model for substrate loading to the periplasmic vestibule of the type II secretion system. The drawing encompasses periplasmic domains of GspL (blue), GspM (grey), GspC (dark grey), the secretin channel (light grey) and a molecule of a cargo protein (black) viewed from the top of the secretion machinery. In the proposed model the transient tetramerization of GspLperi is proposed as a mechanism to open the periplasmic vestibule and to enable entry of an exoprotein (left). In contrast, the channel is closed when the GspLperi dimers are equivalently distributed (right).
