2MZ9

Solution structure of oxidized triheme cytochrome PpcA from Geobacter sulfurreducens

Summary for 2MZ9

• Entry DOI: 10.2210/pdb2mz9/pdb
• NMR Information: BMRB: 25477
• Descriptor: PpcA, HEME C (2 entities in total)
• Functional Keywords: cytochrome, paramagnetic, electron transport
• Biological source: Geobacter sulfurreducens
• Total number of polymer chains: 1
• Total formula weight: 9603.66

Authors

Morgado, L.,Bruix, M.,Pokkuluri, R.,Salgueiro, C.A.,Turner, D.L. (deposition date: 2015-02-08, release date: 2016-02-10, Last modification date: 2024-05-01)

Primary citation

Morgado, L.,Bruix, M.,Pokkuluri, P.R.,Salgueiro, C.A.,Turner, D.L.
Redox- and pH-linked conformational changes in triheme cytochrome PpcA from Geobacter sulfurreducens.
Biochem. J., 474:231-246, 2017

PubMed Abstract: The periplasmic triheme cytochrome PpcA from Geobacter sulfurreducens is highly abundant; it is the likely reservoir of electrons to the outer surface to assist the reduction of extracellular terminal acceptors; these include insoluble metal oxides in natural habitats and electrode surfaces from which electricity can be harvested. A detailed thermodynamic characterization of PpcA showed that it has an important redox-Bohr effect that might implicate the protein in e/H coupling mechanisms to sustain cellular growth. This functional mechanism requires control of both the redox state and the protonation state. In the present study, isotope-labeled PpcA was produced and the three-dimensional structure of PpcA in the oxidized form was determined by NMR. This is the first solution structure of a G. sulfurreducens cytochrome in the oxidized state. The comparison of oxidized and reduced structures revealed that the heme I axial ligand geometry changed and there were other significant changes in the segments near heme I. The pH-linked conformational rearrangements observed in the vicinity of the redox-Bohr center, both in the oxidized and reduced structures, constitute the structural basis for the differences observed in the pK values of the redox-Bohr center, providing insights into the e/H coupling molecular mechanisms driven by PpcA in G. sulfurreducens.

PubMed: 28062839
DOI: 10.1042/BCJ20160932

Experimental method

SOLUTION NMR