A Preliminary Study On The Regulatory Networks Of Drug-resistant Genes In Mycoplasma Pneumoniae Based On Proteomics Analyses

[OBJECTIVE] Mycoplasma pneumoniae is one of major pathogens in community-acquired pneumonia. At present, macrolide-resistant Mycoplasma pneumoniae are dramatically growing worldwide. However, there were few intensive studies on the mechanism of macrolide-resistance. Most studies focused on the mutation detection for macrolide-binding site or epidemiological investigation. This study aimed at exploring mechanism of macrolide-resistance at the protein level in order to identify new proteins related with macrolide-resistance and to investigate relevant gene regulatory networks.[METHODS] The MICs of macrolides (erythromycin and azithromycin) were detected for Mp isolated strains by employing broth microdilution assay. Proteome of the macrolide-resistant strains (S20 and S56)were compared with the proteome of the macroli de-sensitive wild strain (FH) by iTRAQ labeling and LC-MS/MS for protein identification. Making FH as a control group, we finded out primer target proteins with higher expression in both S20 and S56. Bioinformatics analysis, such as GO, COG and KEGG functional analysis, were used to annotate these proteins. Verification of target proteins were carried out at the DNA level with a method of RT-PCR in a large sample. Then final target proteins relating to macrolide-resistance were indentified.[RESUILS] Of 496 proteins identified,10 were at least 1.2-fold more or less abundant in S20 compared with FH. And 18 are at least 1.2-fold more or less abundant in S56 compared with FH.7 proteins were included in both groups above, but the group of S20 vs. S56. Molecular function and biological process of these proteins were well annotated by bioinformatics analysis. However, no evidence was found that the 7 proteins related to other mechanisms of macrolide-resistance. The verification results of RT-PCR analysis in a sample of 53 strains showed that MPN480 and MPN277 were more highly expressed in erythromycin-resistant strains than in erythromycin-sensitive strains.[CONCLUSION] MPN480 and MPN277 could be potential molecular markers of macrolide-resistance at protein level, but further studies in a larger sample were still needed. Our study represents the first comparative analysis of large-scale quantitative proteomics on the mechanism of drug-resistance in Mp.