Fig. 2.

Channel in the HpnN transporter. (A) Channel formed by each subunit of the form I structure of HpnN. Each channel is colored gray. The Left and Right subunits of HpnN are colored yellow and red, respectively. (B) Channel formed by each subunit of the form II structure of HpnN. Each channel is colored gray. The Left and Right subunits of HpnN are colored green and orange, respectively. The calculations were done using the program CAVER (loschmidt.chemi.muni.cz/caver). (C) Schematic representation illustrating the channel is open in each subunit of the form I structure of HpnN. The HpnN transporter may use this open channel to shuttle hopanoid molecules to the outer membrane. (D) Schematic representation illustrating the channel is closed in each subunit of the form II structure of HpnN. In this conformation, hopanoid molecules may not be able to pass through the channel.