Cell-penetrating peptidomimetics derived from cathelicidin CAP-18 showed inhibition of Na+ /K+, Cu(I) and Zn(II)ATPases in mycobacterial plasma membrane

Abstract

Aims & objectives: Mycobacterium tuberculosis is the etiological agent of tuberculosis (TB), which is one of the ten most deadly diseases and the first cause of death by bacterial origin around the world. One of the causes that increase the problem are the M. tuberculosis resistant strains to conventional antibiotics, multi-drug resistant tuberculosis (MDR-TB) and extensively-drug resistant tuberculosis (XDR-TB); so it is necessary to develop new drugs with different mechanisms of action. Methods: In this study, the effect on the mycobacterial cell membrane ATPase activity of CAP-18 derived peptide with unnatural amino acids was assessed. Using bioinformatic tools, the amino acid sequence of CAP-18 with the best features of helical structure and antibacterial activity was determined; the corresponding peptide had changes for D-Lys and N-methyl-Gly in the sequence, generating the peptides CAP18-BD and CAP18-CD and the peptoid CAP18-BP. Results: In vitro assesament of the peptides and peptidomimetics were tested in plasma membrame from Mycobacterium smegmatis mc2 155. The inorganic phosphate released (Pi) was quantified during the ATP hydrolysis reaction by the action of ATPases, using the Fiske and Subarrow method modified by Cariani et al., in the presence and absence of the peptidic sequences to be evaluated, where the basal ATPase activity in the absence corresponds to zero percent inhibition of these enzymes, and 100% of the residual ATPase activity, understood as the enzymatic activity present with or without peptide treatment. Conclusions: The results showed inhibition of basal ATPase activity and Na+ /K+, Cu(I), Zn (II) pumps in the plasma membrane, which is associated with its mechanism of action, which suggests that CAP18-BD, CAP18-CD and CAP18-BP can be considered as a potential antimycobacterial compounds targeting cell membrane ATPases.