Small membranous proteins of the TorE/NapE family, crutches for cognate respiratory systems in Proteobacteria

Abstract

In this report, we investigate small proteins involved in bacterial alternative respiratory systems that improve the enzymatic efficiency through better anchorage and multimerization of membrane components. Using the small protein TorE of the respiratory TMAO reductase system as a model, we discovered that TorE is part of a subfamily of small proteins that are present in proteobacteria in which they play a similar role for bacterial respiratory systems. We reveal by microscopy that, in Shewanella oneidensis MR1, alternative respiratory systems are evenly distributed in the membrane contrary to what has been described for Escherichia coli. Thus, the better efficiency of the respiratory systems observed in the presence of the small proteins is not due to a specific localization in the membrane, but rather to the formation of membranous complexes formed by TorE homologs with their c-type cytochrome partner protein. By an in vivo approach combining Clear Native electrophoresis and fluorescent translational fusions, we determined the 4:4 stoichiometry of the complexes. In addition, mild solubilization of the cytochrome indicates that the presence of the small protein reinforces its anchoring to the membrane. Therefore, assembly of the complex induced by this small protein improves the efficiency of the respiratory system.

The structure of the F420-dependent sulfite-detoxifying enzyme from Methanococcales reveals a prototypical sulfite-reductase with assimilatory traits

“…The cells were sonicated 4 x 70 % intensity for 10 seconds, followed by a 30 second break (MS 73 probe, SONOPULS Bandelin). The hrCN PAGE was run anaerobically and the protocol was adapted from Lemaire et al (2018 (52)). The detailed procedure of hrCN running conditions can be found in the supporting information.…”

Shewanella decolorationis LDS1 Chromate Resistance

“…sesselensis [CP037898]) was isolated from a sample of sediments collected in a pond at the Anse Coco beach (La Digue Island, Republic of Seychelles, Indian Ocean) on the basis of its capability to grow on rich medium containing trimethylamine oxide (TMAO). Indeed, the latter is a compound widespread in marine environments, and, with a few exceptions, it is used as a major respiratory substrate by Shewanella species (28)(29)(30)(31). Based on a comparison of the conserved 16S rRNA genes of over thirty Shewanella species, a phylogenetic tree was constructed ( Fig.…”

Structural Insights into the Methane-Generating Enzyme from a Methoxydotrophic Methanogen Reveal a Restrained Gallery of Post-Translational Modifications

“…The hrCN-PAGE protocol was adapted from Lemaire et al [ 30 ]. Glycerol (20% v/v final) was added to samples and 0.001% w/v Ponceau S was used as a protein migration marker.…”