Characterisation of electron transport in a bacterial nano-wire protein through high performance computing and experimentation

Lead Research Organisation: University of East Anglia
Department Name: Chemistry

Abstract

Day to day life is increasingly reliant on electricity to support transport and communications in addition to the storage and preparation of food. This situation reflects rapid scientific developments since Alessandro Volta built the first battery just over 200 years ago. However electricity has been essential to humans, and indeed all forms of cellular life, ever since they have existed. This electricity arises from the electron transport chains underpinning the storage of solar energy in sugars during photosynthesis and the harnessing of the energy in sugars for cellular function, reproduction and motility during respiration. Specially designed proteins support electron transport during photosynthesis and respiration. Many of these proteins contain metal ions positioned at regular intervals within a polymer made of amino acids and we can immediately see parallels to the structures of the much larger cables and wires that move electrons in our mobile phones, toasters etc. The properties determining the flow of electrons through cables and wires are well established. However, the means by which a particular amino acid structure defines the rate of electron transfer within and between such proteins when dissolved in water is less well understood. Here we propose to provide insight into these mechanisms through a combination of computational and experimental methods. The subject of our study is an iron-containing protein, whose three-dimensional structure has been solved only a few months ago. This protein is a representative of a large family of structurally related, but functionally distinct, proteins that has been recognised only recently. These proteins allow microbes to colonise diverse and apparently inhospitable environments. They contribute to the operation of some microbial fuel-cells and to the virulence of numerous microbes capable of infecting humans and animals. By resolving the molecular details underpinning electron transport through these proteins we will provide fundamental insight into a wide-spread and important mechanism of biological electron transport. Some of the computational methods are already available and some of them need to be developed during the research programme. The new methodologies will be made available to other scientists for studying other proteins of interest. The knowledge gained will also provide the framework for developing proteins with bespoke electrical properties for use as molecular nano-wires in bioelectronic engineering.
 
Description Multiheme cytochromes play essential roles in moving electrons across the outermembranes of bacteria allowing electron exchange between extracelluar and intracellular environments. We have developed a method for light-driven electron injection into purified multiheme cytochromes. Transient absorbance has revealed the contributions of multiple conformers to charge separation and charge recombination in the photosensitised proteins. Continuous irradiation of the photosensitised proteins has shown they are able to pass electrons to other redox proteins providing a potential route to study inter-protein electron transfer. Measurements of solid state conductance has revealed a tetraheme cytochrome supports much higher conductance that proteins of equivalent dimension with either a single heme, or Cu center. Through protein engineering we have increased the lifetime of the charge separated state in a manner that should allow more effective coupling of light-driven electron transfer and chemical catalysis through (semi-)artificial photosynthesis.
Exploitation Route There is considerable interest in developing electron exchange between extracellular electrodes and intracellular processes for the sustainable production of electricity and chemicals. With the aim of producing high-value products from readily available oxidized precursors, bacteria can receive electrons from cathodes to drive reductive intracellular transformations and the opportunities for such microbial electrosynthesis attracts much interest for carbon dioxide sequestration and niche industrial application. Bioremediation can be coupled to electricity production, for example in microbial fuel cells, when the direction of electron transfer is reversed and electrons are delivered to an anode from intracellular oxidative transformations. Multiheme cytochromes underpin these processes and our findings could underpin the development of novel photosystems and allow measurement of rates of electron transfer through multiheme cytochromes to underpin rational improvements in biotechnology for sustainable electricity and chemicals production.
Sectors Chemicals,Electronics,Energy,Manufacturing, including Industrial Biotechology

 
Description Workshop on Protein Electrochemistry BISON
Geographic Reach Europe 
Policy Influence Type Influenced training of practitioners or researchers
Impact New skills and approaches to research were displayed by the participants after completing the course.
 
Description Biohybrids for Solar Chemicals and Fuels: Whole-cell Photocatalysis by Non-photosynthetic Organisms.
Amount £1,220,000 (GBP)
Funding ID BB/S002499/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 01/2019 
End 12/2021
 
Description Royal Society Leverhulme Trust Senior Research Fellowship
Amount £54,000 (GBP)
Organisation The Royal Society 
Department Royal Society Leverhulme Trust Senior Research Fellowship
Sector Charity/Non Profit
Country United Kingdom
Start 10/2015 
End 09/2016
 
Description Solid state electronic conduction in multiheme cytochromes 
Organisation Weizmann Institute of Science
Country Israel 
Sector Academic/University 
PI Contribution Multiheme cytochrome designed to have single cysteine adjacent to terminus of heme wire at defined site on surface was designed and purified.
Collaborator Contribution Measurements of solid state conductance by the aforementioned multiheme cytochrome were performed.
Impact Manuscript describing key findings has been submitted for peer-review. Multi-disciplinary: physics, biophysics, biochemistry, theoretical chemistry.
Start Year 2017
 
Description Anglian Water Discussion 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact Technology Director for Anglian Water visited UEA and spoke with research leaders on a number of projects identified as having potential interest to their business. The use of bacteria in 'sludge' to produce electricity was a novel concept to the Director, follow up e-mails passed on relevant technical reports and literature.
Year(s) Of Engagement Activity 2017
 
Description Interactive Display at Latitude Festival, Suffolk, 2018 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact >1100 people visited our interactive display over 3 days in the Kids Zone at Latitude festival. Through experiments, games and virtual reality our visitors learnt about different types of energy, interconversion of types of energy,microbial fuel cells, electricity producing bacteria and proteins that conduct electricity across cell walls. Our engaging activities sparked lively discussion among our visitors and it was clear that they all (kids, parents and grandparents) left us with a great excitement for science.
Year(s) Of Engagement Activity 2018
URL https://www.sawtrust.org/news/latitude-festival-2018/
 
Description Interactive Display at Norwich Science Festival October 2018 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The Forum, in the centre of Norwich, was the location for our interactive display during a day of the Norwich Science Festival. Through experiments, games and virtual reality our visitors learnt about different types of bacteria, learnt about microbial fuel cells and electrically conductive proteins. There were > 1000 visitors and informal feedback showed they had learnt something new about sustainable technology, physics and biology from their visit.
Year(s) Of Engagement Activity 2018
URL https://norwichsciencefestival.co.uk/
 
Description Norwich Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Demonstrations of microbial fuel cells accompanied by virtual reality headsets that allowed a 'journey' through the bacteria to see the enzymes key to operation of the fuel cell. Much discussion and questions arising from this.
Year(s) Of Engagement Activity 2016,2017
 
Description Press Release MHC review 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact not known
Year(s) Of Engagement Activity 2014
 
Description Public Talk 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact An informal presentation on 'biobatteries' and extracellular electron transfer at pub in Norwich City Centre. Attended by approximately 30 members of public including school teachers and electrical engineers.
Year(s) Of Engagement Activity 2017
URL https://www.meetup.com/Norwich-Biomakers/events/243884032/?_cookie-check=XxyoJwuy8pUP8Sx_
 
Description Royal Norfolk Show 2016 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact Over 2 days many representatives from industry/business in addition to general public and school children visited our display and engaged in discussion about our research, its possible technological impact and the underlying scientific principles.
Year(s) Of Engagement Activity 2016,2017
 
Description Royal Norfolk Show 2017 Education Zone 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Prior to the event Local Schools supplied soil from their grounds. This was loaded into Microbial Fuel Cells and their performance (power output and longevity) was reported at the Royal Norfolk Show alongside virtual reality experience of extracellular electron transfer process for H2 production and a short talk covering key principles of biological H2 production.
Year(s) Of Engagement Activity 2017
 
Description School visit (Norwich) with experiments 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact science workshops for key stage 1 (5 - 7 yr)
Year(s) Of Engagement Activity 2016,2017
 
Description Talk at IET meeting Shrewsbury March 2019 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Presentation at a meeting of The Institution of Engineering and Technology in Shrewsbury. The significance of bio-electricity to ATP production was explained, electricity production by bacteria was explained and microbial fuel cells demonstrated and discussed. Our related, new research into (semi-)artificial photosynthesis was introduced. Discussion after the talk was lively and touched on wide-ranging topics.
Year(s) Of Engagement Activity 2019
 
Description Talk at Norwich Science Festival October 2019 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact A talk on electrically conductive proteins and electricity producing bacteria. There were lots of questions and discussion, during and after the talk. From those it was clear that the topics sparked lots of interest in the physics of biology and new approaches to eco-friendly electricity production.
Year(s) Of Engagement Activity 2018
URL https://norwichsciencefestival.co.uk/
 
Description UEA Open Day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact interactive demonstrations run throughout the day prompted ongoing discussions with visitors about our research.

many people noted the research was fascinating and they were not aware of it previously
Year(s) Of Engagement Activity 2010,2011,2012,2013,2014