Characterization of the periplasmic redox network that sustains the versatile anaerobic metabolism of Shewanella oneidensis MR-1
Year: 2015
Type: article
Abstract: The versatile anaerobic metabolism of the Gram-negative bacterium Shewanella oneidensis MR-1 (SOMR-1) relies on a multitude of redox proteins found in its periplasm. Most are multiheme cytochromes that carry electrons to terminal reductases of insoluble electron acceptors located at the cell surface, or bona fide terminal reductases of soluble electron acceptors. In this study, the interaction network of several multiheme cytochromes was explored by a combination of NMR spectroscopy, activity assays followed by UV-visible spectroscopy and comparison of surface electrostatic potentials. From these data the small tetraheme cytochrome (STC) emerges as the main periplasmic redox shuttle in SOMR-1. It accepts electrons from CymA and distributes them to a number of terminal oxidoreductases involved in the respiration of various compounds. STC is also involved in the electron transfer pathway to reduce nitrite by interaction with the octaheme tetrathionate reductase (OTR), but not with cytochrome c nitrite reductase (ccNiR). In the main pathway leading the metal respiration STC pairs with flavocytochrome c (FccA), the other major periplasmic cytochrome, which provides redundancy in this important pathway. The data reveals that the two proteins compete for the binding site at the surface of MtrA, the decaheme cytochrome inserted on the periplasmic side of the MtrCAB-OmcA outer-membrane complex. However, this is not observed for the MtrA homologues. Indeed, neither STC nor FccA interact with MtrD, the best replacement for MtrA, and only STC is able to interact with the decaheme cytochrome DmsE of the outer-membrane complex DmsEFABGH. Overall, these results shown that STC plays a central role in the anaerobic respiratory metabolism of SOMR-1. Nonetheless, the trans-periplasmic electron transfer chain is functionally resilient as a consequence of redundancies that arise from the presence of alternative pathways that bypass/compete with STC.
Source: Frontiers in Microbiology
Language: English
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,801
Awards: INVESTIGATING THE MOLECULAR DETAILS OF THE MULTI-ELECTRON REDUCTION OF NITROGEN COMPOUNDS BY OTR, A METALLOENZYME INVOLVED IN THE BIOGEOCHEMICAL CYCLE OF NITROGEN, Mecanismos moleculares que coordenam um passo de dois electrões acoplado à protonação em enzimas redox contendo uma rede de cofactores redox de um electrão, G5734021361, EMERGING HUMAN PATHOGENS FROM THE SHEWANELLA GENUS: UNDERSTANDING THE MOLECULAR MECHANISM BEHIND FERRIC IRON-SIDEROPHORE REDUCTION, NMR Net - Centro Nacional de Ressonância Magnética Nuclear: desde a Estrutura e Dinâmica Moleculares à Função Proteica, Fisiologia Celular e Metabolómica
OpenAlex ID: W1486588564