<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="6.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Liliana R. Teixeira</style></author><author><style face="normal" font="default" size="100%">Fernandes, Tomás M.</style></author><author><style face="normal" font="default" size="100%">Silva, , Marta A.</style></author><author><style face="normal" font="default" size="100%">Leonor Morgado</style></author><author><style face="normal" font="default" size="100%">Salgueiro, , Carlos A.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Characterization of a novel cytochrome involved in Geobacter sulfurreducens’ electron harvesting pathways</style></title><secondary-title><style face="normal" font="default" size="100%">Chemistry – A European Journal</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Biomolecular interactions</style></keyword><keyword><style  face="normal" font="default" size="100%">c-Type cytochrome</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron transfer</style></keyword><keyword><style  face="normal" font="default" size="100%">Microbial electrosynthesis</style></keyword><keyword><style  face="normal" font="default" size="100%">Nuclear magnetic resonance</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2022</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202202333</style></url></web-urls></urls><number><style face="normal" font="default" size="100%">n/a</style></number><volume><style face="normal" font="default" size="100%">n/a</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Electron harvesting bacteria are key targets to develop microbial electrosynthesis technologies, which are valid alternatives for the production of value-added compounds without utilization of fossil fuels. Geobacter sulfurreducens, that is capable of donating and accepting electrons from electrodes, is one of the most promising electroactive bacteria. Its electron transfer mechanisms to electrodes have been progressively elucidated, however the electron harvesting pathways are still poorly understood. Previous studies showed that the periplasmic cytochromes PccH and GSU2515 are overexpressed in current-consuming G. sulfurreducens biofilms. PccH was characterized, though no putative partners have been identified. In this work, GSU2515 was characterized by complementary biophysical techniques and in silico simulations using the AlphaFold neural network. GSU2515 is a low-spin monoheme cytochrome with a disordered N-terminal region and an α-helical C-terminal domain harboring the heme group. The cytochrome undergoes a redox-linked heme axial ligand switch, with Met91 and His94 as distal axial ligand in the reduced and oxidized state, respectively. The reduction potential of the cytochrome is negative and is modulated by the pH in the physiological range: -78 mV at pH 6 and -113 mV at pH 7. Such pH-dependence coupled to the redox-linked switch of the axial ligand allows the cytochrome to drive a proton-coupled electron transfer step that is crucial to confer directionality to the respiratory chain. Biomolecular interactions and electron transfer experiments indicated that GSU2515 and PccH form a redox complex. Overall, the data obtained highlights for the first time how periplasmic proteins bridge the electron transfer between the outer and inner membrane in the electron harvesting pathways of G. sulfurreducens.&lt;/p&gt;
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