Biomolecular interaction studies between cytochrome PpcA from geobacter sulfurreducensand the electron acceptor ferric nitrilotriacetate (Fe-NTA)

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Abstract

Geobacter sulfurreducens bacterium exhibits an enormous respiratory versatility, including the utilization of several toxic and radioactive metals as electron acceptors. This versatility is also replicated in the capability of the most abundant cytochrome in G. sulfurreducens, the periplasmic triheme cytochrome PpcA, to reduce uranium, chromium and other metal ions. From all possible electron transfer pathways in G. sulfurreducens, those involved in the iron reduction are the best characterized to date. Previously, we provided structural evidence for the complex interface established between PpcA and the electron acceptor Fe(III)-citrate. However, genetic studies suggested that this acceptor is mainly reduced by outer membrane cytochomes. In the present work, we used UV-visible measurements to demonstrate that PpcA is able to directly reduce the electron acceptor ferric nitrilotriacetate (Fe-NTA), a more outer membrane permeable iron chelated form. In addition, the molecular interactions between PpcA and Fe-NTA were probed by Nuclear Magnetic Resonance (NMR) spectroscopy. The NMR spectra obtained for PpcA samples in the absence and presence of Fe-NTA showed that the interaction is reversible and encompasses a positively charged surface region located in the vicinity of the heme IV. Overall, the study elucidates the formation of an electron transfer complex between PpcA and a readily outer-membrane permeable iron chelated form. The structural and functional relationships obtained explain how a single cytochrome is designed to effectively interact with a wide range of G. sulfurreducens electron acceptors, a feature that can be explored for optimal bioelectrochemical applications.

Original languageEnglish
Article number2741
JournalFrontiers in Microbiology
Volume9
Issue numberNOV
DOIs
Publication statusPublished - 16 Nov 2018

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Geobacter
Cytochromes
Electrons
Iron
Membranes
Magnetic Resonance Spectroscopy
Metals
Uranium
Poisons
Chromium
Heme
Citric Acid
5'-deoxy-5'-phosphonomethyladenosine phosphate
ferric nitrilotriacetate
Ions
Bacteria

Keywords

  • Biomolecular interactions
  • Electron transfer
  • Geobacter
  • Iron respiration
  • Multiheme cytochrome

Cite this

@article{fb0aee2004f14e96999aacb046020543,
title = "Biomolecular interaction studies between cytochrome PpcA from geobacter sulfurreducensand the electron acceptor ferric nitrilotriacetate (Fe-NTA)",
abstract = "Geobacter sulfurreducens bacterium exhibits an enormous respiratory versatility, including the utilization of several toxic and radioactive metals as electron acceptors. This versatility is also replicated in the capability of the most abundant cytochrome in G. sulfurreducens, the periplasmic triheme cytochrome PpcA, to reduce uranium, chromium and other metal ions. From all possible electron transfer pathways in G. sulfurreducens, those involved in the iron reduction are the best characterized to date. Previously, we provided structural evidence for the complex interface established between PpcA and the electron acceptor Fe(III)-citrate. However, genetic studies suggested that this acceptor is mainly reduced by outer membrane cytochomes. In the present work, we used UV-visible measurements to demonstrate that PpcA is able to directly reduce the electron acceptor ferric nitrilotriacetate (Fe-NTA), a more outer membrane permeable iron chelated form. In addition, the molecular interactions between PpcA and Fe-NTA were probed by Nuclear Magnetic Resonance (NMR) spectroscopy. The NMR spectra obtained for PpcA samples in the absence and presence of Fe-NTA showed that the interaction is reversible and encompasses a positively charged surface region located in the vicinity of the heme IV. Overall, the study elucidates the formation of an electron transfer complex between PpcA and a readily outer-membrane permeable iron chelated form. The structural and functional relationships obtained explain how a single cytochrome is designed to effectively interact with a wide range of G. sulfurreducens electron acceptors, a feature that can be explored for optimal bioelectrochemical applications.",
keywords = "Biomolecular interactions, Electron transfer, Geobacter, Iron respiration, Multiheme cytochrome",
author = "Ferreira, {Marisa R.} and Salgueiro, {Carlos A.}",
note = "info:eu-repo/grantAgreement/FCT/5876/147258/PT# This work was supported by Funda{\cc}{\~a}o para a Ci{\^e}ncia e a Tecnologia (FCT-MCTES) through the following grants: SFRH/BD/132969/2017 (MRF); PTDC/BBB-BQB/3554/2014 (to CAS). This work was also supported by Unidade de Ci{\^e}ncias Biomoleculares Aplicadas-UCIBIO which is financed by national funds from FCT/MEC (UID/Multi/04378/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007728). The NMR spectrometers are part of the National NMR Network (PTNMR) and are supported by Infrastructure Project No. 022161 (co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT through PIDDAC).",
year = "2018",
month = "11",
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doi = "10.3389/fmicb.2018.02741",
language = "English",
volume = "9",
journal = "Frontiers in Microbiology",
issn = "1664-302X",
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number = "NOV",

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TY - JOUR

T1 - Biomolecular interaction studies between cytochrome PpcA from geobacter sulfurreducensand the electron acceptor ferric nitrilotriacetate (Fe-NTA)

AU - Ferreira, Marisa R.

AU - Salgueiro, Carlos A.

N1 - info:eu-repo/grantAgreement/FCT/5876/147258/PT# This work was supported by Fundação para a Ciência e a Tecnologia (FCT-MCTES) through the following grants: SFRH/BD/132969/2017 (MRF); PTDC/BBB-BQB/3554/2014 (to CAS). This work was also supported by Unidade de Ciências Biomoleculares Aplicadas-UCIBIO which is financed by national funds from FCT/MEC (UID/Multi/04378/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007728). The NMR spectrometers are part of the National NMR Network (PTNMR) and are supported by Infrastructure Project No. 022161 (co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT through PIDDAC).

PY - 2018/11/16

Y1 - 2018/11/16

N2 - Geobacter sulfurreducens bacterium exhibits an enormous respiratory versatility, including the utilization of several toxic and radioactive metals as electron acceptors. This versatility is also replicated in the capability of the most abundant cytochrome in G. sulfurreducens, the periplasmic triheme cytochrome PpcA, to reduce uranium, chromium and other metal ions. From all possible electron transfer pathways in G. sulfurreducens, those involved in the iron reduction are the best characterized to date. Previously, we provided structural evidence for the complex interface established between PpcA and the electron acceptor Fe(III)-citrate. However, genetic studies suggested that this acceptor is mainly reduced by outer membrane cytochomes. In the present work, we used UV-visible measurements to demonstrate that PpcA is able to directly reduce the electron acceptor ferric nitrilotriacetate (Fe-NTA), a more outer membrane permeable iron chelated form. In addition, the molecular interactions between PpcA and Fe-NTA were probed by Nuclear Magnetic Resonance (NMR) spectroscopy. The NMR spectra obtained for PpcA samples in the absence and presence of Fe-NTA showed that the interaction is reversible and encompasses a positively charged surface region located in the vicinity of the heme IV. Overall, the study elucidates the formation of an electron transfer complex between PpcA and a readily outer-membrane permeable iron chelated form. The structural and functional relationships obtained explain how a single cytochrome is designed to effectively interact with a wide range of G. sulfurreducens electron acceptors, a feature that can be explored for optimal bioelectrochemical applications.

AB - Geobacter sulfurreducens bacterium exhibits an enormous respiratory versatility, including the utilization of several toxic and radioactive metals as electron acceptors. This versatility is also replicated in the capability of the most abundant cytochrome in G. sulfurreducens, the periplasmic triheme cytochrome PpcA, to reduce uranium, chromium and other metal ions. From all possible electron transfer pathways in G. sulfurreducens, those involved in the iron reduction are the best characterized to date. Previously, we provided structural evidence for the complex interface established between PpcA and the electron acceptor Fe(III)-citrate. However, genetic studies suggested that this acceptor is mainly reduced by outer membrane cytochomes. In the present work, we used UV-visible measurements to demonstrate that PpcA is able to directly reduce the electron acceptor ferric nitrilotriacetate (Fe-NTA), a more outer membrane permeable iron chelated form. In addition, the molecular interactions between PpcA and Fe-NTA were probed by Nuclear Magnetic Resonance (NMR) spectroscopy. The NMR spectra obtained for PpcA samples in the absence and presence of Fe-NTA showed that the interaction is reversible and encompasses a positively charged surface region located in the vicinity of the heme IV. Overall, the study elucidates the formation of an electron transfer complex between PpcA and a readily outer-membrane permeable iron chelated form. The structural and functional relationships obtained explain how a single cytochrome is designed to effectively interact with a wide range of G. sulfurreducens electron acceptors, a feature that can be explored for optimal bioelectrochemical applications.

KW - Biomolecular interactions

KW - Electron transfer

KW - Geobacter

KW - Iron respiration

KW - Multiheme cytochrome

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U2 - 10.3389/fmicb.2018.02741

DO - 10.3389/fmicb.2018.02741

M3 - Article

VL - 9

JO - Frontiers in Microbiology

JF - Frontiers in Microbiology

SN - 1664-302X

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