Jessica Wonderen - Academia.edu (original) (raw)

Papers by Jessica Wonderen

Spectroscopic, electrochemical and voltammetric data desribing properties of photosensitized MtrC... more Spectroscopic, electrochemical and voltammetric data desribing properties of photosensitized MtrC proteins. The data are presented as figures in van Wonderen et al 'Nanosecond heme-to-heme electron transfer rates in a spectrally unique His/Met-ligated heme', the manuscript and supporting information appendix.<br>

Data from spectroscopic, electrochemical, voltammetric and computational studies as presented in ... more Data from spectroscopic, electrochemical, voltammetric and computational studies as presented in van Wonderen et al 'Nanosecond heme-to-heme electron transfer rates in a multiheme cytochrome nanowire reported by a spectrally unique His/Met-ligated heme'. Data presented in the Main and Supporting Information Appendix are included.<br>

Microbial nanowires are fascinating biological structures allowing bacteria to transport electron... more Microbial nanowires are fascinating biological structures allowing 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 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.

Frontiers in Microbiology, 2021

Shewanella oneidensis exchanges electrons between cellular metabolism and external redox partners... more Shewanella oneidensis exchanges electrons between cellular metabolism and external redox partners in a process that attracts much attention for production of green electricity (microbial fuel cells) and chemicals (microbial electrosynthesis). A critical component of this pathway is the outer membrane spanning MTR complex, a biomolecular wire formed of the MtrA, MtrB, and MtrC proteins. MtrA and MtrC are decaheme cytochromes that form a chain of close-packed hemes to define an electron transfer pathway of 185 Å. MtrA is wrapped inside MtrB for solubility across the outer membrane lipid bilayer; MtrC sits outside the cell for electron exchange with external redox partners. Here, we demonstrate tight and spontaneous in vitro association of MtrAB with separately purified MtrC. The resulting complex is comparable with the MTR complex naturally assembled by Shewanella in terms of both its structure and rates of electron transfer across a lipid bilayer. Our findings reveal the potential fo...

arXiv: Biological Physics, 2020

Multi-heme cytochromes (MHC) are fascinating proteins used by bacterial organisms to shuttle elec... more Multi-heme cytochromes (MHC) are fascinating proteins used by bacterial organisms to shuttle electrons within and between their cells. When placed in a solid state electronic junction, they support temperature-independent currents over several nanometers that are three orders of magnitude higher compared to other redox proteins of comparable size. To gain microscopic insight into their astonishingly high conductivities, we present herein the first current-voltage calculations of its kind, for a MHC sandwiched between two Au(111) electrodes, complemented by photo-emission spectroscopy experiments. We find that conduction proceeds via off-resonant coherent tunneling mediated by a large number of protein valence-band orbitals that are strongly delocalized over heme and protein residues, effectively "gating" the current between the two electrodes. This picture is profoundly different from the dominant electron hopping mechanism supported by the same protein in aqueous solution...

Proceedings of the National Academy of Sciences, 2021

Significance Multiheme cytochromes have been identified as essential proteins for electron exchan... more Significance Multiheme cytochromes have been identified as essential proteins for electron exchange between bacterial enzymes and redox substrates outside of the cell. In microbiology, these proteins contribute to efficient energy storage and conversion. For biotechnology, multiheme cytochromes contribute to the production of green fuels and electricity. Furthermore, these proteins inspire the design of molecular-scale electronic devices. Here, we report exceptionally high rates of heme-to-heme electron transfer in a multiheme cytochrome. We expect similarly high rates, among the highest reported for ground-state electron transfer in biology, in other multiheme cytochromes as the close-packed hemes adopt similar configurations despite very different amino acid sequences and protein folds.

The Journal of Physical Chemistry Letters, 2020

Multi-heme cytochromes (MHCs) are fascinating proteins used by bacterial organisms to shuttle ele... more Multi-heme cytochromes (MHCs) are fascinating proteins used by bacterial organisms to shuttle electrons within, between, and out of their cells. When placed in solid-state electronic junctions, MHCs support temperature-independent currents over several nanometers that are 3 orders of magnitude higher compared to other redox proteins of similar size. To gain molecular-level insight into their astonishingly high conductivities, we combine experimental photoemission spectroscopy with DFT+Σ current−voltage calculations on a representative Gold-MHC-Gold junction. We find that conduction across the dry, 3 nm long protein occurs via off-resonant coherent tunneling, mediated by a large number of protein valence-band orbitals that are strongly delocalized over heme and protein residues. This picture is profoundly different from the electron hopping mechanism induced electrochemically or photochemically under aqueous conditions. Our results imply that the current output in solid-state junctions can be even further increased in resonance, for example, by applying a gate voltage, thus allowing a quantum jump for next-generation bionanoelectronic devices.

Journal of the American Chemical Society, 2019

Multiheme cytochromes attract much attention for their electron transport properties. These prote... more Multiheme cytochromes attract much attention for their electron transport properties. These proteins conduct electrons across bacterial cell walls, along extracellular filaments, and when purified can serve as bionanoelectronic junctions. Thus, it is important and necessary to identify and understand the factors governing electron transfer in this family of proteins. To this end we have used ultra-fast transient absorbance spectroscopy, to define heme-heme electron transfer dynamics in the representative multiheme cytochrome STC from Shewanella oneidensis in aqueous solution. STC was photo-sensitized by site-selective labelling with a Ru(II)(bipyridine) 3 dye and the dynamics of light-driven electron transfer described by a kinetic model corroborated by molecular dynamics simulation and density functional theory calculations. With the dye attached adjacent to STC Heme IV, a rate constant of 87  10 6 s-1 was resolved for Heme IV  Heme III electron transfer. With the dye attached adjacent to STC Heme I, at the opposite terminus of the tetraheme chain, a rate constant of 125  10 6 s-1 was defined for Heme I  Heme II electron transfer. These rates are an order of magnitude faster than previously computed values for unlabeled STC. The Heme III/IV and I/II pairs exemplify the T-shaped heme packing arrangement, prevalent in multiheme cytochromes, whereby the adjacent porphyrin rings lie at 90 o with edge-edge (Fe-Fe) distances of 6 (11) Å. The results are significant in demonstrating the opportunities for pumpprobe spectroscopies to resolve inter-heme electron transfer in Ru-labeled multiheme cytochromes. Introduction: Species of Shewanella attract much interest for their ability to respire in the absence of oxygen by transferring electrons from intracellular oxidation of organic matter to extracellular acceptors including Fe 2 O 3 and MnO 2 nanoparticles. 1-2 Multiheme cytochromes are essential to this process and these fascinating proteins are spanned by chains of close-packed c-type hemes. Intra-and inter-cytochrome electron transfer occurs by complementary Fe(III)  Fe(II) transitions of neighboring sites 3-5 and in this way electrons are moved from the inner bacterial membrane, across the periplasm and outer membrane lipid bilayer to reach the cell exterior. Multiheme cytochromes also contribute to the conductivity of extracellular structures, often termed bacterial nanowires, which transfer electrons across distances greatly exceeding cellular dimensions. These structures for Shewanella oneidensis are multiheme cytochrome containing extensions of the bacterial outer membrane 6 and for Geobacter sulfurreducens are filaments 7-8 comprised of a polymerized multiheme cytochrome. Beyond their biological role, the remarkable electron transfer properties of multiheme cytochromes have stimulated interest in these proteins as novel bioelectronic junctions and devices. 9-12 Furthermore, these proteins underpin the wiring of bacteria to electrodes 1, 13-15 to produce electricity in mediator-less microbial fuel cells and valued chemicals by microbial

Chemical Science, 2018

We study solvent-free electron transport across two multi-heme cytochrome c-type proteins, MtrF a... more We study solvent-free electron transport across two multi-heme cytochrome c-type proteins, MtrF and STC, and find that they are better at conducting than non- or mono heme proteins.

Methods in Enzymology, 2018

Certain bacterial species have a natural ability to exchange electrons with extracellular redox p... more Certain bacterial species have a natural ability to exchange electrons with extracellular redox partners. This behavior allows coupling of catalytic transformations inside bacteria to complementary redox transformations of catalysts and electrodes outside the cell. Electricity generation can be coupled to waste-water remediation. Industrially relevant oxidation reactions proceed exclusively when electrons are released to anodes. Reduced products such as fuels can be generated when electrons are provided from (photo)cathodes. Rational development of these opportunities and inspiration for novel technologies is underpinned by resolution at the molecular level of pathways supporting electron exchange across bacterial cell envelopes. This chapter describes methods for purification, engineering and in vitro characterization of proteins providing the primary route for electron transport across the outer membrane lipid bilayer of Shewanella oneidensis MR-1, a well-described electrogenic bacterium and chassis organism for related biotechnologies.

Chembiochem : a European journal of chemical biology, Jan 18, 2018

Multiheme cytochromes possess closely packed redox-active hemes arranged as chains spanning the t... more Multiheme cytochromes possess closely packed redox-active hemes arranged as chains spanning the tertiary structure. Here we describe five variants of a representative multiheme cytochrome engineered as biohybrid phototransducers converting light to electricity. Each variant possesses a single Cys-sulfhydryl near a terminus of the heme chain and that was efficiently labelled with a Ru(II)(bipyridine)3 photosensitiser. When irradiated in the presence of a sacrificial electron donor the proteins exhibited different behaviours. Certain proteins were rapidly and fully reduced. Other proteins were rapidly semi-reduced but resisted complete photo-reduction. These findings reveal photosensitised multiheme cytochromes can be engineered to act as resistors, with intrinsic regulation of light-driven electron accumulation, and also as molecular wires with essentially unhindered photo-reduction. The observed behaviours are proposed to arise from interplay between the site of electron injection a...

Biophysical Chemistry, 2015

Prokaryotic metal-ion receptor proteins, or solute-binding proteins, facilitate the acquisition o... more Prokaryotic metal-ion receptor proteins, or solute-binding proteins, facilitate the acquisition of metal ions from the extracellular environment. Pneumococcal surface antigen A (PsaA) is the primary Mn 2+-recruiting protein of the human pathogen Streptococcus pneumoniae and is essential for its in vivo colonization and virulence. The recently reported high-resolution structures of metalfree and metal-bound PsaA have provided the first insights into the mechanism of PsaA-facilitated metal binding. However, the conformational dynamics of metal-free PsaA in solution remain unknown. Here, we use continuous wave electron paramagnetic resonance (EPR) spectroscopy and molecular dynamics (MD) simulations to study the relative flexibility of the structural domains in metal-free PsaA and its distribution of conformations in solution. The results show that the crystal structure of the metal-free PsaA is a good representation of the dominant conformation in solution, but the protein also samples structurally distinct conformations that are not captured by the crystal structure. The results also suggest that the metal binding site is larger and more solvent exposed than indicated by the metal-free crystal structure. This study provides atomic-resolution insight into the conformational dynamics of PsaA prior to metal binding and lay the groundwork for future EPR and MD based studies of PsaA in solution.

Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2014

Globins and Other Nitric Oxide-Reactive Proteins, Part B, 2008

The periplasmic cytochrome c nitrite reductase (Nrf) system of Escherichia coli utilizes nitrite ... more The periplasmic cytochrome c nitrite reductase (Nrf) system of Escherichia coli utilizes nitrite as a respiratory electron acceptor by reducing it to ammonium. Nitric oxide (NO) is a proposed intermediate in this six-electron reduction and NrfA can use exogenous NO as a substrate. This chapter describes the method used to assay Nrf-catalyzed NO reduction in whole cells of E. coli and the procedures for preparing highly purified NrfA suitable for use in kinetic, spectroscopic, voltammetric, and crystallization studies.

Theoretical Chemistry Accounts, 2007

FEBS Journal, 2014

Understanding the process that underlies multi-drug recognition and efflux by P-glycoprotein (ABC... more Understanding the process that underlies multi-drug recognition and efflux by P-glycoprotein (ABCB1) remains a key biological challenge. Structural data has recently become available for the murine and C. elegans homologues of ABCB1; however all structures were obtained in the absence of nucleotide. A feature of these structures was the presence of a central cavity that is inaccessible from the extracellular face of the protein. To determine the conformational dynamics of this region several residues in transmembrane helices TM6 (331, 343 and 354) and TM12 (980) were mutated to cysteine. Based upon structural predictions these residues are proposed to line, or

Langmuir, 2012

Oxidation is the most commonly used method of passivating porous silicon (PSi) surfaces against u... more Oxidation is the most commonly used method of passivating porous silicon (PSi) surfaces against unwanted reactions with guest molecules and temporal changes during storage or use. In the present study, several oxidation methods were compared in order to find optimal methods able to generate inert surfaces free of reactive hydrides but would cause minimal changes in the pore structure of PSi. The studied methods included thermal oxidations, liquid-phase oxidations, annealings, and their combinations. The surface-oxidized samples were studied by Fourier transform infrared spectroscopy, isothermal titration microcalorimetry, nitrogen sorption, ellipsometry, X-ray diffraction, electron paramagnetic resonance spectroscopy, and scanning electron microscopy imaging. Treatment at high temperature was found to have two advantages. First, it enables the generation of surfaces free of hydrides, which is not possible at low temperatures in a liquid or a gas phase. Second, it allows the silicon framework to partially accommodate a volume expansion because of oxidation, whereas at low temperature the volume expansion significantly consumes the free pore volume. The most promising methods were further optimized to minimize the negative effects on the pore structure. Simple thermal oxidation at 700 °C was found to be an effective oxidation method although it causes a large decrease in the pore volume. A novel combination of thermal oxidation, annealing, and liquid-phase oxidation was also effective and caused a smaller decrease in the pore volume with no significant change in the pore diameter but was more complicated to perform. Both methods produced surfaces that were not found to react with a model drug cinnarizine in isothermal titration microcalorimetry experiments. The study enables a reasonable choice of oxidation method for PSi applications.

Journal of Biological Chemistry, 2008

Cytochrome c nitrite reductase (NrfA) from Escherichia coli has a well established role in the re... more Cytochrome c nitrite reductase (NrfA) from Escherichia coli has a well established role in the respiratory reduction of nitrite to ammonium. More recently the observation that anaerobically grown E. coli nrf mutants were more sensitive to NO⅐ than the parent strain led to the proposal that NrfA might also participate in NO⅐ detoxification. Here we describe protein film voltammetry that presents a quantitative description of NrfA NO⅐ reductase activity. NO⅐ reduction is initiated at similar potentials to NrfA-catalyzed reduction of nitrite and hydroxylamine. All three activities are strongly inhibited by cyanide. Together these results suggest a common site for reduction of all three substrates as axial ligands to the lysine-coordinated NrfA heme rather than nonspecific NO⅐ reduction at one of the four His-His coordinated hemes also present in each NrfA subunit. NO⅐ reduction by NrfA is described by a K m of the order of 300 M. The predicted turnover number of ϳ840 NO⅐ s ؊1 is much higher than that of the dedicated respiratory NO⅐ reductases of denitrification and the flavorubredoxin and flavohemoglobin of E. coli that are also proposed to play roles in NO⅐ detoxification. In considering the manner by which anaerobically growing E. coli might detoxify exogenously generated NO⅐ encountered during invasion of a human host it appears that the periplasmically located NrfA should be effective in maintaining low NO⅐ levels such that any NO⅐ reaching the cytoplasm is efficiently removed by flavorubredoxin (K m ϳ 0.4 M).