Molecular detection of H. pylori antibiotic-resistant genes and molecular docking analysis.

To explore the mutation characteristics of H. pylori resistance-related genes to antibiotics of clarithromycin (CAM), levofloxacin (LVX) and metronidazole, 23SrRNA, gyrA, gyrB, rdxA, and frxA genes were amplified and sequenced, respectively. Molecular docking study was performed to explore molecular interactions between chemotherapeutic agents and target proteins. In the CAM-resistant strains, the mutation rate in site A2143G was 74.2% (n = 23). The interactions in sites of G1949A, C1953T, and G2211T with CAM were weaker after mutation. In the LVX-resistant strains, the mutation rates in 87 (N to K/I) and 91 (D to N/Y/G) of gyrA were 28.6% (n = 16) and 12.5% (n = 7), respectively. We could infer by docking studies that N87 K/I, D91Y/G/N, D99N, and D143E mutations in GyrA protein all had weakened interaction with LVX. The mutation types of RdxA protein consisted of protein truncation caused by premature stop codons (n = 26, 33.3%), frameshift mutations (n = 8, 10.3%), FMN-binding sites (n = 16, 20.5%), and the others (n = 11, 14.1%). Docking analysis showed that some mutations in those four types of RdxA protein could reduce interaction with MNZ, and play a significant role in antibiotic resistance. What's more, we performed natural transformation with some of these mutated DNA fragments to see if they really impact susceptibility to antibiotics. Our study suggested that in addition to the reported mutation sites, H. pylori antibiotic resistance in this region may also be associated with changes in some new sites. Our study provides novel ideas and methods for the identification of H. pylori resistance-related mutations, and also clues and basis for further investigation on specific molecular mechanism.