Rapid publication of new ideas: proteome + phosphorylation group reveals the mechanism of nanomaterials to promote biofilm formation

In March 2022, Peng Zhang's research team from Xiangtan University published a paper entitled "Quantitative proteomics and phosphoproteomics elucidate the molecular mechanism of nanostructured TiO 2" at the Journal of Hazardous Materials (IF_14.

nTiO₂，Escherichia coli K12

Technical route

Step 1:_nTiO2 selectively enriches bacterial pathogens and increases the diversity of microbial communities;

Step 2: Proteomics and phosphorylation modification omics analysis of E.

Step 3:_nTiO2 promotes biofilm production by enhancing the absorption of iron;

Step 4:_nTiO2 improves E.

Step 5:_nTiO2 increases biofilm production

Research results

1.

The researchers added 0, 5 and 50 mg/L nTiO2 to the activated sludge, respectively, and observed the growth of biofilms under stress conditions for 30 h

2.

In order to analyze the mechanism of nTiO2 promoting biofilm formation, E.

3.

Through proteomic analysis of E.

Figure 4 Effect of_nTiO2 on microbial iron acquisition systems

4.
nTiO2 improves E.
coli adaptability to antimicrobial agents by enhancing transcriptional and translation processes

To delve into whether E.
coli responds to nTiO2 stress by regulating transcriptional and translational processes, the researchers added different types of transcriptional and protein synthesis inhibitors to the bacterial medium to analyze the effect
of nTiO2 on E.
coli fitness.
The results showed that the biofilm content of the_nTiO2 exposure group under the protein synthesis inhibitor tetracycline treatment was comparable to that of the control group, indicating that the protein synthesis process was not involved in regulating the adaptability
of E.
coli to nTiO2 stress.
The biofilm content of the nTiO2 exposure group under the transcriptional inhibitor rifampicin treatment was significantly higher than that in the control group, indicating that nTiO2 increased the adaptability
of E.
coli by regulating the transcriptional process.
_nTiO2 treatment led to significant downregulation of the phosphorylated modification of rifampicin's target protein RpoB, which is the main mechanism
by which nTiO2 improves E.
coli resistance to transcriptional inhibitors.

Figure 5 Study of resistance of E.
coli to protein synthesis inhibitors and transcriptional inhibitors

5.
nTiO2 increases biofilm production by dephosphorylation of CsgD

CsgD is a key transcriptional regulator that has been reported to regulate the formation of E.
coli biofilm, regulating the synthesis of extracellular polysaccharides, fimbria and cellulose, which, as a linear polysaccharide polymer, is an important protective scaffold
for biofilm formation.
The omics results of this study showed that nTiO2 treatment induced CsgD phosphorylation modification levels were significantly downregulated, while BcsB, BcsZ, BcsC, SecG, and SesY related to biofilm synthesis were significantly upregulated
in protein levels.
The dephosphorylated form of CsgD specifically binds to the adrA promoter region and activates its transcription, while AdrA typically mediates protein synthesis of cellulose
by upregulating cyclic diguanyridine levels to proteins such as BcsBAZC.
In summary, the change in phosphorylation modification of the csgD protein induced by nTiO2 mediated the regulatory process of E.
coli biofilm formation, thereby affecting the adaptability
of E.
coli to sub-lethal concentrations of nTiO2.

Figure 6 Effect of_nTiO2 on extracellular components during biofilm matrix formation

Summary

Although the interactions between nanomaterials and microbes have broad ecological and health implications, the mechanisms by which microbes adapt to nanomaterials remain unclear
.
In this study, biofilm biomass formed in activated sludge exposed to_nTiO2 under dark conditions increased and pathogens were selectively enriched.

The results of proteomics analysis showed that nTiO2 stress further led to overexpression of the ferrocarrist of conditioned pathogenic bacteria, which enhanced their resistance through dephosphorylation of the associated transcriptional translation protein
.
_nTiO2 promotes biofilm production and improves the adaptability of pathogenic bacteria, which in turn accelerates biological contamination, leading to potential ecological and health risks.