title: DnaK protein alleviates toxicity induced by citrate-coated gold nanoparticles in Escherichia coli.
abstract: A number of previously reported studies suggest that synthetic gold nanoparticles (AuNPs) are capable of stabilising proteins against heat stress in vitro. However, it remains to be understood if AuNPs confer stability to proteins against cellular stress in vivo. Heat shock proteins (Hsps) are conserved molecules whose main role is to facilitate folding of other proteins (chaperone function). Hsp70 (called DnaK in prokaryotes) is one of the most prominent molecular chaperones. Since gold nanoparticles exhibit chaperone-like function in vitro, we investigated the effect of citrate-coated gold nanoparticles on the growth of E. coli BB1553 cells that possess a deleted dnaK gene. We further investigated the effects of the AuNPs on the solubility of the E. coli BB1553 proteome. E. coli BB1553 cells exposed to AuNPs exhibited cellular defects such as filamentation and plasma membranes pulled off the cell wall. The toxic effects of the AuNPs were alleviated by transforming the E. coli BB1553 cells with a construct expressing DnaK. We also noted that cells in which DnaK was restored exhibited distinct zones to which the nanoparticles were restricted. Our study suggests a role for DnaK in alleviating nanoparticle induced stress in E. coli.
authors.affiliation: Department of Biochemistry, School of Mathematics & Natural Sciences, University of Venda, Thohoyandou, South Africa; Department of Biochemistry & Microbiology, University of Zululand, KwaDlangezwa, South Africa.
authors.forename: Stanley
authors.initials: S
authors.lastname: Makumire
authors.affiliation: Department of Chemistry, University of Zululand, KwaDlangezwa, South Africa.
authors.forename: Neerish
authors.initials: N
authors.lastname: Revaprasadu
authors.affiliation: Department of Biochemistry, School of Mathematics & Natural Sciences, University of Venda, Thohoyandou, South Africa; Department of Biochemistry & Microbiology, University of Zululand, KwaDlangezwa, South Africa.
authors.forename: Addmore
authors.initials: A
authors.lastname: Shonhai
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000235:genetics / Q000648:ultrastructure; D002473:Cell Wall / Q000187:drug effects / Q000235:genetics / Q000648:ultrastructure; D019343:Citric Acid / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000235:genetics*; D005816:Genetic Complementation Test; D006046:Gold / Q000737:chemistry / Q000633:toxicity*; D018840:HSP70 Heat-Shock Proteins / Q000172:deficiency / Q000235:genetics*; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D046529:Microscopy, Electron, Transmission; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D020543:Proteome / Q000235:genetics* / Q000378:metabolism; D012995:Solubility; D014169:Transformation, Bacterial
chemical_list: D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D020543:Proteome; D019343:Citric Acid; D006046:Gold; C063842:dnaK protein, E coli
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