A unique aromatic residue modulates the redox range of a periplasmic multiheme cytochrome from Geobacter metallireducens.
Geobacter
NMR
bioenergetics
cytochrome c
electron transfer
site-directed mutagenesis
Journal
The Journal of biological chemistry
ISSN: 1083-351X
Titre abrégé: J Biol Chem
Pays: United States
ID NLM: 2985121R
Informations de publication
Date de publication:
Historique:
received:
12
03
2021
revised:
21
04
2021
accepted:
23
04
2021
pubmed:
30
4
2021
medline:
20
8
2021
entrez:
29
4
2021
Statut:
ppublish
Résumé
Geobacter bacteria are able to transfer electrons to the exterior of the cell and reduce extracellular electron acceptors including toxic/radioactive metals and electrode surfaces, with potential applications in bioremediation or electricity harvesting. The triheme c-type cytochrome PpcA from Geobacter metallireducens plays a crucial role in bridging the electron transfer from the inner to the outer membrane, ensuring an effective extracellular electron transfer. This cytochrome shares 80% identity with PpcA from Geobacter sulfurreducens, but their redox properties are markedly different, thus determining the distinctive working redox potential ranges in the two bacteria. PpcA from G. metallireducens possesses two extra aromatic amino acids (Phe-6 and Trp-45) in its hydrophobic heme core, whereas PpcA from G. sulfurreducens has a leucine and a methionine in the equivalent positions. Given the different nature of these residues in the two cytochromes, we have hypothesized that the extra aromatic amino acids could be partially responsible for the observed functional differences. In this work, we have replaced Phe-6 and Trp-45 residues by their nonaromatic counterparts in PpcA from G. sulfurreducens. Using redox titrations followed by UV-visible and NMR spectroscopy we observed that residue Trp-45 shifted the redox potential range 33% toward that of PpcA from G. sulfurreducens, whereas Phe-6 produced a negligible effect. For the first time, it is shown that the inclusion of an aromatic residue at the heme core can modulate the working redox range in abundant periplasmic proteins, paving the way to engineer bacterial strains for optimal microbial bioelectrochemical applications.
Identifiants
pubmed: 33915126
pii: S0021-9258(21)00500-7
doi: 10.1016/j.jbc.2021.100711
pmc: PMC8163978
pii:
doi:
Substances chimiques
Cytochromes
0
Heme
42VZT0U6YR
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
100711Informations de copyright
Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.
Déclaration de conflit d'intérêts
Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article.
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