UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Kinetics of trifurcated electron flow in the decaheme bacterial proteins MtrC and MtrF

Jiang, X; Burger, B; Gajdos, F; Bortolotti, C; Futera, Z; Breuer, M; Blumberger, J; (2019) Kinetics of trifurcated electron flow in the decaheme bacterial proteins MtrC and MtrF. Proceedings of the National Academy of Sciences of The United States of America 10.1073/pnas.1818003116. (In press). Green open access

[thumbnail of main.pdf]
Preview
Text
main.pdf - Accepted Version

Download (4MB) | Preview

Abstract

The bacterium Shewanella oneidensis has evolved a sophisticated electron transfer (ET) machinery to export electrons from the cytosol to extracellular space during extracellular respiration. At the heart of this process are decaheme proteins of the Mtr pathway, MtrC and MtrF, located at the external face of the outer bacterial membrane. Crystal structures have revealed that these proteins bind 10 c-type hemes arranged in the peculiar shape of a staggered cross that trifurcates the electron flow, presumably to reduce extracellular substrates while directing electrons to neighboring multiheme cytochromes at either side along the membrane. Especially intriguing is the design of the heme junctions trifurcating the electron flow: they are made of coplanar and T-shaped heme pair motifs with relatively large and seemingly unfavorable tunneling distances. Here, we use electronic structure calculations and molecular simulations to show that the side chains of the heme rings, in particular the cysteine linkages inserting in the space between coplanar and T-shaped heme pairs, strongly enhance electronic coupling in these two motifs. This results in an [Formula: see text]-fold speedup of ET steps at heme junctions that would otherwise be rate limiting. The predicted maximum electron flux through the solvated proteins is remarkably similar for all possible flow directions, suggesting that MtrC and MtrF shuttle electrons with similar efficiency and reversibly in directions parallel and orthogonal to the outer membrane. No major differences in the ET properties of MtrC and MtrF are found, implying that the different expression levels of the two proteins during extracellular respiration are not related to redox function.

Type: Article
Title: Kinetics of trifurcated electron flow in the decaheme bacterial proteins MtrC and MtrF
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1073/pnas.1818003116
Publisher version: https://doi.org/10.1073/pnas.1818003116
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Density functional theory, electron transfer, extracellular respiration, heme, molecular dynamics
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10069122
Downloads since deposit
116Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item