Which multi-heme protein complex transfers electrons more efficiently? Comparing MtrCAB from Shewanella with OmcS from Geobacter

Xiuyun Jiang, Jessica Van Wonderen, Julea Butt, Marcus J. Edwards, Tom Clarke, Jochen Blumberger

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)
9 Downloads (Pure)


Microbial nanowires are fascinating biological structures that allow bacteria to transport electrons over micrometers for reduction of extracellular substrates. It was recently established that the nanowires of both Shewanella and Geobacter are made of multi-heme proteins; but, while Shewanella employs the 20-heme protein complex MtrCAB, Geobacter uses a redox polymer made of the hexa-heme protein OmcS, begging the question as to which protein architecture is more efficient in terms of long-range electron transfer. Using a multiscale computational approach we find that OmcS supports electron flows about an order of magnitude higher than MtrCAB due to larger heme-heme electronic couplings and better insulation of hemes from the solvent. We show that heme side chains are an essential structural element in both protein complexes, accelerating rate-limiting electron tunnelling steps up to 1000-fold. Our results imply that the alternating stacked/T-shaped heme arrangement present in both protein complexes may be an evolutionarily convergent design principle permitting efficient electron transfer over very long distances.

Original languageEnglish
Pages (from-to)9421–9425
Number of pages5
JournalThe Journal of Physical Chemistry Letters
Issue number21
Early online date26 Oct 2020
Publication statusPublished - 5 Nov 2020

Cite this