Mefloquine and new related compounds target the F(0) complex of the F(0)F(1) H(+)-ATPase of Streptococcus pneumoniae.
The activities of mefloquine (MFL) and related compounds against previously characterized Streptococcus pneumoniae strains carrying defined amino acid substitutions in the c subunit of the F(0)F(1) H(+)-ATPase were studied. In addition, a series of MFL-resistant (Mfl(r)) strains were isolated and characterized. A good correlation was observed between inhibition of growth and inhibition of the membrane-associated F(0)F(1) H(+)-ATPase activity. MFL was about 10-fold more active than optochin and about 200-fold more active than quinine in inhibiting both the growth and the ATPase activities of laboratory pneumococcal strain R6. Mutant strains were inhibited by the different compounds to different degrees, depending on their specific mutations in the c subunit. The resistant strains studied had point mutations that changed amino acid residues in either the c subunit or the a subunit of the F(0) complex. Changes in the c subunit were located in one of the two transmembrane alpha helices: residues M13, G14, G20, M23, and N24 of helix 1 and residues M44, G47, V48, A49, and V57 of helix 2. Changes in the a subunit were also found in either of the transmembrane alpha helices, helix 5 or 6: residue L186 of helix 5 and residues W206, F209, and S214 of helix 6. These results suggest that the transmembrane helices of the c and a subunits interact and that the mutated residues are important for the structure of the F(0) complex and proton translocation.
Martín-Galiano
Antonio Javier
AJ
Unidad de Genética Bacteriana (Consejo Superior de Investigaciones Científicas), Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain.
Gorgojo
Begoña
B
Kunin
Calvin M
CM
de la Campa
Adela G
AG
D000595:Amino Acid Sequence; D000605:Amino Alcohols / Q000494:pharmacology; D000962:Antimalarials / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004269:DNA, Bacterial / Q000235:genetics; D015767:Mefloquine / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D006180:Proton-Translocating ATPases / Q000187:drug effects* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics
D000605:Amino Alcohols; D000962:Antimalarials; D004269:DNA, Bacterial; D006180:Proton-Translocating ATPases; D015767:Mefloquine