Secretion of metal-binding proteins by a newly discovered OsmY homolog in Cupriavidus metallidurans for the biogenic synthesis of metal nanoparticles

Abstract

A newly discovered OsmY protein homolog of Cupriavidus metallidurans for use in protein secretion and biogenic synthesis of nanoparticles.

Proteomic responses to gold(iii)-toxicity in the bacterium Cupriavidus metallidurans CH34

“…The Cu chaperone protein, CupC, was used for further analysis, as this was the only protein to contain a metal binding domain that could be responsible for binding Au-complexes. 18 A model of the Cu chaperon protein was constructed based on two related Cu-binding proteins: a 'multispecies' copper chaperone, heavy metal binding (modular protein) of an organism described solely as Cupriavidus (WP_00864966) which had a 100% homology between amino acids 68-133 with the Cu chaperon protein identified in this study, and a copper chaperone from Cupriavidus sp. BIS7 (WP_019451883); the resulting protein model is shown in Fig.…”

“…However, the presence of Cu(I)-binding sites demonstrates that the protein CupC contains metal-binding sites that are suitable for Au(I)-binding, due to chemical similarity Au complexes are predicted to bind to Cu-binding sites. 4 In addition, a study by Ouyang et al, 18 showed that Au nanoparticles were formed in the presence of truncated CupC fused to the secretion carrier Rmet_3428, suggesting the binding of Au to a metal-binding motif in CupC. Overall, this highlights the limitations of computer-based protein modelling, which relies on the utilisation of suitable datasets that is not available for the Au-complex studied.…”

“…17 In another study addition of Au(III)-complexes to the supernatant of a C. metallidurans culture, which had expressed truncated CupC, resulted in the formation of Au nanoparticles; note: truncated CupC contained its metal-binding motif and was fused to secretion carrier Rmet_3428, a homolog of known secretion-carrier OsmY found in Escherichia coli. 18 However, the majority of studies investigating the response of C. metallidurans to Au(I/III) have relied on transcriptomics. 8,13,15 Transcriptomics uses the amount of mRNA in a cell as an indicator of cellular function, but mRNA abundance is not necessarily indicative of protein abundance or cellular function.…”