Selection of Staphylococcus aureus DNA replication inhibitors

Abstract

Introduction: S. aureus is an important pathogen that causes nosocomial infections, food poisoning by release of enterotoxins and toxic shock syndrome through the injection of super antigens into the bloodstream.

The β-clamp protein of S. aureus is a process-promoting factor for most enzymes in prokaryotic DNA replication and its dimerization is essential for the deleterious action of the pathogen.

Objective: In this work, we report the application of the double hybrid system to select β-clamp dimerization inhibitors of S. aureus from Caatinga plant extracts, especially Buchenavia tetraphylla.

Material and Methods: (1) preparation of organic extracts of Buchenavia tetraphylla was prepared as previously reported (2) The β-clamp-β-clamp interaction was evaluated using a hybrid double bacterial system (BTH), based on the reconstitution of the activity of the enzyme adenylate cyclase (cya) from Bordetella pertussis and cloned in Escherichia coli. (3) The antimicrobial activity of active extracts was evaluated by determining the minimum inhibitory concentration (MIC) against S. aureus 8325-4 (4) To identify compounds potentially responsible for the activity, the active extracts were subjected to a non-segmented analysis by LC-MS/Q-TOF (5) The in silico studies were carried out by searching for the ligand structures, construction and validation of the 3D model of the β-clamp and molecular docking between ligands and protein target of S. aureus and the human CYP3A4 hepatic system.

Results and Discussion: There was a high interaction (in the order of 4,800 kcal/mol) between buchenavianine and analogues with β-clamp with no significant difference between them. On the other hand, the interaction between buchenavianine and human CYP3A4 analogues was (of the order of 2,200 kcal/mol) following the same principles of electronegativity of the elements. The purpose of this analysis is to understand how the β-clamp protein interacts with the main human liver metabolization protein. The interaction between buchenavianine and human CYP3A4 analogues was 2 times lower than buchenavianine and S. aureus β-clamp analogues, and this shows that between the two targets studied here (S. aureus β-clamp and human CYP3A4) the ligands will be preferentially attracted to the S. aureus β-clamp, which ratifies them as viable inhibitors of the S. aureus DNA replication process.

Conclusion: The combination of microbiological, chemical and computational resources allowed to indicate molecules present in the plant extract capable of interacting with the β-clamp of S. aureus. The approach presented here promotes a rational biochemical screening for ligand selection with better possibilities for subsequent bench tests, saving financial resources and optimizing results in drug research and development.

DOI:https://doi.org/10.56238/sevened2024.003-050