Limits...
DnaK protein alleviates toxicity induced by citrate-coated gold nanoparticles in Escherichia coli.

Makumire S, Revaprasadu N, Shonhai A - PLoS ONE (2015)

Bottom Line: We further investigated the effects of the AuNPs on the solubility of the E. coli BB1553 proteome.The toxic effects of the AuNPs were alleviated by transforming the E. coli BB1553 cells with a construct expressing DnaK.Our study suggests a role for DnaK in alleviating nanoparticle induced stress in E. coli.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


Related in: MedlinePlus

Citrate-coated gold nanoparticles suppress malate dehydrogenase aggregation in a concentration dependent manner.(A) 1 μM MDH was suspended in assay buffer in the absence or presence of various levels of AuNPs (2.5–7.5 μgmL-1). (B) The assay was repeated in the presence of 10 fold higher levels of AuNPs (25–75 μgmL-1). The suspensions were subjected to heat stress at 48°C for 20 minutes. The soluble fraction (S) was separated from pellet fraction (P) by centrifugation. Samples were analysed by SDS-PAGE analysis.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4383610&req=5

pone.0121243.g005: Citrate-coated gold nanoparticles suppress malate dehydrogenase aggregation in a concentration dependent manner.(A) 1 μM MDH was suspended in assay buffer in the absence or presence of various levels of AuNPs (2.5–7.5 μgmL-1). (B) The assay was repeated in the presence of 10 fold higher levels of AuNPs (25–75 μgmL-1). The suspensions were subjected to heat stress at 48°C for 20 minutes. The soluble fraction (S) was separated from pellet fraction (P) by centrifugation. Samples were analysed by SDS-PAGE analysis.

Mentions: In order to further investigate the effect of citrate-coated AuNPs on the integrity of protein under heat stress conditions we exposed MDH, an aggregation prone protein, to heat stress at 48°C in the absence and presence of the citrate-coated AuNPs at low concentration range (2.5–7.5 μgmL-1) and ten-fold higher levels (25–75 μgmL-1). In the absence of AuNPs nearly all the MDH subjected to heat stress aggregated (Fig. 5A-B; lane “0”). However, the aggregation of MDH was suppressed in the presence of AuNPs at lower concentration range (2.5–7.5 μgmL-1; Fig. 5A). On the other hand AuNPs at higher levels (25–75 μgmL-1) were less effective in suppressing MDH aggregation (Fig. 5B).


DnaK protein alleviates toxicity induced by citrate-coated gold nanoparticles in Escherichia coli.

Makumire S, Revaprasadu N, Shonhai A - PLoS ONE (2015)

Citrate-coated gold nanoparticles suppress malate dehydrogenase aggregation in a concentration dependent manner.(A) 1 μM MDH was suspended in assay buffer in the absence or presence of various levels of AuNPs (2.5–7.5 μgmL-1). (B) The assay was repeated in the presence of 10 fold higher levels of AuNPs (25–75 μgmL-1). The suspensions were subjected to heat stress at 48°C for 20 minutes. The soluble fraction (S) was separated from pellet fraction (P) by centrifugation. Samples were analysed by SDS-PAGE analysis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383610&req=5

pone.0121243.g005: Citrate-coated gold nanoparticles suppress malate dehydrogenase aggregation in a concentration dependent manner.(A) 1 μM MDH was suspended in assay buffer in the absence or presence of various levels of AuNPs (2.5–7.5 μgmL-1). (B) The assay was repeated in the presence of 10 fold higher levels of AuNPs (25–75 μgmL-1). The suspensions were subjected to heat stress at 48°C for 20 minutes. The soluble fraction (S) was separated from pellet fraction (P) by centrifugation. Samples were analysed by SDS-PAGE analysis.
Mentions: In order to further investigate the effect of citrate-coated AuNPs on the integrity of protein under heat stress conditions we exposed MDH, an aggregation prone protein, to heat stress at 48°C in the absence and presence of the citrate-coated AuNPs at low concentration range (2.5–7.5 μgmL-1) and ten-fold higher levels (25–75 μgmL-1). In the absence of AuNPs nearly all the MDH subjected to heat stress aggregated (Fig. 5A-B; lane “0”). However, the aggregation of MDH was suppressed in the presence of AuNPs at lower concentration range (2.5–7.5 μgmL-1; Fig. 5A). On the other hand AuNPs at higher levels (25–75 μgmL-1) were less effective in suppressing MDH aggregation (Fig. 5B).

Bottom Line: We further investigated the effects of the AuNPs on the solubility of the E. coli BB1553 proteome.The toxic effects of the AuNPs were alleviated by transforming the E. coli BB1553 cells with a construct expressing DnaK.Our study suggests a role for DnaK in alleviating nanoparticle induced stress in E. coli.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


Related in: MedlinePlus