User:Nikhil Malvankar/Geobacter pilus structure and function: Difference between revisions

The pilus filament is assembled from <scene name='83/834714/Dimer/5'>heterodimers</scene>. Dimer <scene name='83/834714/Dimer/6'>secondary structure</scene>: '''<font color='#e87000'>PilA-N</font>''' consists of two alpha helices, while '''<font color='00a0a0'>PilA-C</font>''' includes a 3-stranded beta sheet. The C-terminal protrusion of '''<font color='#e87000'>PilA-N</font>''' is <scene name='83/834714/Flaps/4'>held between two flaps</scene> (darker) of '''<font color='00a0a0'>PilA-C</font>'''. The flaps have almost no contact with each other. They are held in place by apolar contacts and hydrogen bonds with the C-terminal protrusion of '''<font color='#e87000'>PilA-N</font>'''. These flaps might be open before '''<font color='#e87000'>PilA-N</font>''' arrives to form a dimer, reminiscent of the flaps of HIV protease<ref>PMID: 16418268</ref>. (See, for example, [[1hxw]] and [[Flaps Morph for HIV Protease]].) <scene name='83/834714/Flaps/6'>Four glycines</scene> (<font color="red">'''red: 10, 11, 31, 37'''</font>) provide flexibility that could enable opening of the flaps.