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Title: Structural insights into the modulation of the redox properties of two Geobacter sulfurreducens homologous triheme cytochromes.

Abstract

The redox properties of a periplasmic triheme cytochrome, PpcB from Geobacter sulfurreducens, were studied by NMR and visible spectroscopy. The structure of PpcB was determined by X-ray diffraction. PpcB is homologous to PpcA (77% sequence identity), which mediates cytoplasmic electron transfer to extracellular acceptors and is crucial in the bioenergetic metabolism of Geobacter spp. The heme core structure of PpcB in solution, probed by 2D-NMR, was compared to that of PpcA. The results showed that the heme core structures of PpcB and PpcA in solution are similar, in contrast to their crystal structures where the heme cores of the two proteins differ from each other. NMR redox titrations were carried out for both proteins and the order of oxidation of the heme groups was determined. The microscopic properties of PpcB and PpcA redox centers showed important differences: (1) the order in which hemes become oxidized is III-I-IV for PpcB, as opposed to I-IV-III for PpcA; (2) the redox-Bohr effect is also different in the two proteins. The different redox features observed between PpcB and PpcA suggest that each protein uniquely modulates the properties of their co-factors to assure effectiveness in their respective metabolic pathways. The origins of the observed differencesmore » are discussed.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); Research grants
OSTI Identifier:
939332
Report Number(s):
ANL/BIO/JA-61813
Journal ID: ISSN 0006-3002; BBACAQ; TRN: US200823%%91
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Biochem. Biophys. Acta
Additional Journal Information:
Journal Volume: 1777; Journal Issue: 9 ; Sep. 2008; Journal ID: ISSN 0006-3002
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; BIOLOGICAL PATHWAYS; CRYSTAL STRUCTURE; CYTOCHROMES; ELECTRON TRANSFER; HEME; METABOLISM; MODULATION; OXIDATION; PROTEINS; SPECTROSCOPY; X-RAY DIFFRACTION

Citation Formats

Morgado, L, Bruix, M, Orshonsky, V, Londer, Y Y, Duke, N E. C., Yang, X, Pokkuluri, P R, Schiffer, M, Salgueiro, C A, Biosciences Division, Univ. Nova de Lisboa, and Quimica-Fisica, Insti de. Structural insights into the modulation of the redox properties of two Geobacter sulfurreducens homologous triheme cytochromes.. United States: N. p., 2008. Web. doi:10.1016/j.bbabio.2008.04.043.
Morgado, L, Bruix, M, Orshonsky, V, Londer, Y Y, Duke, N E. C., Yang, X, Pokkuluri, P R, Schiffer, M, Salgueiro, C A, Biosciences Division, Univ. Nova de Lisboa, & Quimica-Fisica, Insti de. Structural insights into the modulation of the redox properties of two Geobacter sulfurreducens homologous triheme cytochromes.. United States. https://doi.org/10.1016/j.bbabio.2008.04.043
Morgado, L, Bruix, M, Orshonsky, V, Londer, Y Y, Duke, N E. C., Yang, X, Pokkuluri, P R, Schiffer, M, Salgueiro, C A, Biosciences Division, Univ. Nova de Lisboa, and Quimica-Fisica, Insti de. 2008. "Structural insights into the modulation of the redox properties of two Geobacter sulfurreducens homologous triheme cytochromes.". United States. https://doi.org/10.1016/j.bbabio.2008.04.043.
@article{osti_939332,
title = {Structural insights into the modulation of the redox properties of two Geobacter sulfurreducens homologous triheme cytochromes.},
author = {Morgado, L and Bruix, M and Orshonsky, V and Londer, Y Y and Duke, N E. C. and Yang, X and Pokkuluri, P R and Schiffer, M and Salgueiro, C A and Biosciences Division and Univ. Nova de Lisboa and Quimica-Fisica, Insti de},
abstractNote = {The redox properties of a periplasmic triheme cytochrome, PpcB from Geobacter sulfurreducens, were studied by NMR and visible spectroscopy. The structure of PpcB was determined by X-ray diffraction. PpcB is homologous to PpcA (77% sequence identity), which mediates cytoplasmic electron transfer to extracellular acceptors and is crucial in the bioenergetic metabolism of Geobacter spp. The heme core structure of PpcB in solution, probed by 2D-NMR, was compared to that of PpcA. The results showed that the heme core structures of PpcB and PpcA in solution are similar, in contrast to their crystal structures where the heme cores of the two proteins differ from each other. NMR redox titrations were carried out for both proteins and the order of oxidation of the heme groups was determined. The microscopic properties of PpcB and PpcA redox centers showed important differences: (1) the order in which hemes become oxidized is III-I-IV for PpcB, as opposed to I-IV-III for PpcA; (2) the redox-Bohr effect is also different in the two proteins. The different redox features observed between PpcB and PpcA suggest that each protein uniquely modulates the properties of their co-factors to assure effectiveness in their respective metabolic pathways. The origins of the observed differences are discussed.},
doi = {10.1016/j.bbabio.2008.04.043},
url = {https://www.osti.gov/biblio/939332}, journal = {Biochem. Biophys. Acta},
issn = {0006-3002},
number = 9 ; Sep. 2008,
volume = 1777,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2008},
month = {Mon Sep 01 00:00:00 EDT 2008}
}