Inhibition of Escherichia coli ATP synthase by amphibian antimicrobial peptides

Abstract

Previously melittin, the α-helical basic honey bee venom peptide, was shown to inhibit F 1 -ATPase by binding at the β-subunit DELSEED motif of F 1 F o ATP synthase. Herein, we present the inhibitory effects of the basic α-helical amphibian antimicrobial peptides, ascaphin-8, aurein 2.2, aurein 2.3, carein 1.8, carein 1.9, citropin 1.1, dermaseptin, maculatin 1.1, maganin II, MRP, or XT-7, on purified F 1 and membrane bound F 1 F o E. coli ATP synthase. We found that the extent of inhibition by amphibian peptides is variable. Whereas MRP-amide inhibited ATPase essentially completely (~96% inhibition), carein 1.8 did not inhibit at all (0% inhibition). Inhibition by other peptides was partial with a range of ~13% to 70%. MRP-amide was also the most potent inhibitor on molar scale (IC 50 ~3.25 µM). Presence of an amide group at the c-terminal of peptides was found to be critical in exerting potent inhibition of ATP synthase (~20-40% additional inhibition). Inhibition was fully reversible and found to be identical in both F 1 F o membrane preparations as well as in isolated purified F 1 . Interestingly, growth of Escherichia coli was abrogated in the presence of ascaphin-8, aurein 2.2, aurein 2.3, citropin 1.1, dermaseptin, magainin II-amide, MRP, MRP-amide, melittin, or melittinamide but was unaffected in the presence of carein 1.8, carein 1.9, maculatin 1.1, magainin II, or XT-7. Hence inhibition of F 1 -ATPase and E. coli cell growth by amphibian antimicrobial peptides suggests that their antimicrobial/anticancer properties are in part linked to their actions on ATP synthase. KeywordsF 1 F o -ATP synthase; F 1 -ATPase; E. coli ATP synthase; Antimicrobial peptides; Amphibian; Enzyme inhibitors F 1 F o -ATP synthase is the primary source of cellular energy production in animals, plants, and almost all microorganisms by oxidative or photophosphorylation. The ATP synthase enzyme is highly conserved and structurally similar in all organisms. This enzyme is the smallest known biological nanomotor and is composed of two rotary sectors, F 1 and F o . In its simplest form in Escherichia coli ATP synthase contains eight different subunits namely α 3 ß 3 γδεab 2 c 10 with a total molecular mass of ~530 kDa. F 1 corresponds to α 3 ß 3 γδε -and F o to ab 2 c 10 . The reversible processess of ATP hydrolysis and synthesis occur on three catalytic sites in the F 1 sector, Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. whereas proton transport occurs through the membrane embedded F o [1][2]. An important feature of the molecular mechanism of ATP synthase is that a "rotor" made up...

Venom peptides cathelicidin and lycotoxin cause strong inhibition of Escherichia coli ATP synthase

“…Previously, several peptides were shown to bind and inhibit E. coli ATP synthase [18, 19, 42, 43]. The lack of desired success in the clinical development of combinatorial chemistry and small molecule based therapies has brought the increased interest in AMPs including venom peptides [44].…”

“…Previously, a number of α-helical amphipathic cationic peptides were shown to bind and inhibit ATPase activity to variable degrees [13, 18, 43, 50, 51]. It was also documented that peptides bind at the highly conserved βDELSEED-motif of ATP synthase [19].…”

“…2). It is interesting to note that in previous studies, many natural and synthetic molecules including peptides caused nil, partial, or total inhibition of ATP synthase [18, 52, 53]. To make sure that the maximal observed inhibition is the true inhibition in the presence of venom peptides, the maximally inhibited samples were re-inhibited.…”

“…The second is bactericidal effect through the inhibition of ATP synthase. It was found that amphibian peptides and melittin, honey bee venom peptide, potently inhibit E. coli ATP synthase leading to the abrogation of E. coli growth [18, 19]. In this study, we examined the inhibitory effects of venom peptides KF-34, BF-30, IL-25, and KE-27 on membrane bound F 1 F o ATP synthase and on the growth of E. coli cells.…”

Use of Peptide Libraries for Identification and Optimization of Novel Antimicrobial Peptides

“…Antimicrobial peptides (AMP's) are not restricted to one mode of action, in fact several cellular target sites have been reported [15], [26]- [28]. The most commonly described target for antimicrobial peptides is the microbial cell membrane.…”