Research On The Mechanism Of SpoVG Regulating The Cytochrome Synthesis Of Staphylococcus Aureus

Staphylococcus aureus is a zoonotic conditional pathogen.It can colonize the nasal cavity and throat of healthy people or animals without causing disease.It can cause a variety of infectious diseases when the host's immunity is low.Staphylococcus aureus with color can produce Staphyloxanthin-SXT,which is an important virulence factor.SXT not only has antioxidant effect,but also has the functions of changing the chemical composition and functional activity of bacteria,reducing the fluidity of cell membrane,and stabilizing the structure of bacteria.Regulating protein Spo VG is one of the important regulatory factors in Staphylococcus aureus to control its toxicity.It is related to the drug resistance of Staphylococcus aureus and the formation of biofilm.However,there are few studies on how Spo VG affects Staphylococcus aureus cytochrome synthesis.This research will take this idea as a starting point to carry out related experiments and researches to explore the molecular mechanism of Spo VG regulation of Staphylococcus aureus cytochrome synthesis.1.The successful construction of SH1000?spo VG,MW2?spo VG and N315?spo VG knockout strains was verified by PCR,and then the growth curve experiment was designed.The results showed that the knockout of spo VG did not affect the growth of SH1000,MW2 and N315 strains.2.Transcriptome sequencing and proteomics analysis of Staphylococcus aureus SH1000 and SH1000?spo VG showed that a total of 132 gene transcripts were defined as DEGs.The knockout of spo VG caused 41 DEGs to be up-regulated and 91 DEGs to be down-regulated..Proteomics results showed that there were 635 significantly different proteins,of which 379 were up-regulated,256 were down-regulated,and there were three differential proteins related to cytochrome synthesis.3.Research the effect of knockout spo VG on cytochrome of Staphylococcus aureus.The results showed that the synthesis ability of cytochrome in Staphylococcus aureus was enhanced after spo VG knockout,that is,Spo VG played a negative regulatory role in cytochrome synthesis.4.The effect of knocking out spo VG on the oxidative stress effect of Staphylococcus aureus was tested by H2O2 pressure experiment and bacterial survival rate experiment.The results showed that when H2O2 was present,the survival rates of SH1000?spo VG and MW2?spo VG increased by 2.2 times and 2.8times,respectively,indicating that spo VG is more effective knockout enhances its oxidative stress stress ability.5.The activity of ?-galactosidase was detected by constructing SH1000/p OS-crt and SH1000?spo VG/p OS-crt reporter plasmid.The results showed that the enzyme activity of SH1000?spo VG/p OS-crt expression ?-galactosidase was higher than that of SH1000/p OS-crt,indicating that spo VG knockdown up-regulated crt promoter activity.The transcription levels of SH1000 and SH1000?spo VG cytochrome-related synthetic gene crt M and ald H were further detected by reverse transcription real-time fluorescence quantitative PCR.The result showed that the transcription levels of crt M and ald H were up-regulated 3.1 and 1.7 times,respectively,compared with the control group,indicating that the regulatory protein Spo VG has a negative regulatory effect on Staphylococcus aureus cytochrome synthesis.