Modeling the Structure of Type IV Pili from Shewanella Oneidensis

Abstract

The metal-reducing bacterium Shewanella oneidensis produces conductive nanowires, which are described as extensions of the outer membrane or type IV pili (T4P), of which the structural details remain unknown. To better understand the structure of S. oneidensis T4P as a nanowire candidate, and the potential mechanism for electron transport along them, theoretical energy-minimized models of these pili were constructed. The models showed a discontinuous geometry consisting of aromatic rings, with large gaps of ∼10 Å, providing a potential pathway for electron hopping, which may account for previously reported conductivity. Moreover, mutations of the pilin subunit based on the models were proposed, which might fill the gaps and possibly increase the conductivity. These models will facilitate further investigation of the nanowires and their applications in bioenergy and bioelectronics.