[Objective] To decipher the regulatory mechanism of a sensor histidine kinase (CusS) inEscherichia coli K-12 in response to silver ion stress and provide scientific evidence for the prevention and treatment of this bacterium. [Methods] ProtParam, ProtScale, Protein-Sol, TMHMM, SignalP, LocTree3, NetNGlyc-1.0, NetPhosBac-3.0, SOPMA, I-TASSERF, STRING, and MEGA were employed to predict the physicochemical properties, hydrophilicity, solubility, transmembrane domain, signal peptides, subcellular localization, glycosylation sites, phosphorylation sites, secondary structure, tertiary structure, protein-protein interaction network of CusS, and the homology of CusS in Gram-negative bacilli, respectively. After that, ΔcusS was constructed by the Red homologous recombination system, and the growth of ΔcusS in different media was monitored. In addition, we evaluated the sensitivity of ΔcusS to silver and copper ions and common antibiotics based on the minimum inhibitory concentration (MIC). RT-qPCR was employed to determine the transcription levels ofcusCFBA andcusR aftercusS deletion. [Results] CusS was composed of 480 amino acid residues, with the relative molecular weight of 53 738.05, the atom number of 7 624, and the isoelectric point of 6.02. It was a hydrophilic and insoluble protein containing transmembrane domain, and no signal peptide, located in the intracellular membrane. CusS had 2 glycosylation sites, 24 serine phosphorylation sites, 14 threonine phosphorylation sites, and 3 tyrosine phosphorylation sites. In the secondary structure, α-helixes, β-sheets, β-turns, and random coils accounted for 55.42%, 11.67%, 3.75%, and 29.17%, respectively. The genecusS was highly conserved inEscherichia andShigella. The colony PCR and first-generation sequencing confirmed the successful construction of ΔcusS. The deletion ofcusS had no influence on the growth or metabolism of the strain. However,cusS was the key gene forE.coli in response to the silver ion stress. [Conclusion] The deletion ofcusS did not affect the growth but attenuated the protective response ofE.coli to silver ion stress. Furthermore, the deletion ofcusS significantly down-regulated the mRNA levels of the downstream genescusCFBA andcusR. The bioinformatics analysis and phenotype characterization of CusS lays a foundation for unveiling the regulatory mechanism of CusS inE.coli in response to silver ion stress.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |